diff --git a/knowledge base/azure/aks.md b/knowledge base/azure/aks.md
index 04179ad..d07a76c 100644
--- a/knowledge base/azure/aks.md	
+++ b/knowledge base/azure/aks.md	
@@ -8,7 +8,6 @@ Managed Kubernetes solution offered by Azure.
 1. [Troubleshooting](#troubleshooting)
    1. [_Subnet XXX does not have enough capacity for YY IP addresses_ while updating the credentials for an existing Service Principal](#subnet-xxx-does-not-have-enough-capacity-for-yy-ip-addresses-while-updating-the-credentials-for-an-existing-service-principal)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -25,15 +24,9 @@ Make sure you have enough space in your cluster's Subnet for at least one new No
 
 - [Update or rotate the credentials for an AKS cluster]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
+<!-- Upstream -->
 [Update or rotate the credentials for an AKS cluster]: https://learn.microsoft.com/en-us/azure/aks/update-credentials
-
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
-<!-- external references -->
diff --git a/knowledge base/azure/bicep.md b/knowledge base/azure/bicep.md
index 08fe116..73af441 100644
--- a/knowledge base/azure/bicep.md	
+++ b/knowledge base/azure/bicep.md	
@@ -13,7 +13,6 @@ The Azure CLI can use a command group (`az bicep …`) to integrate with the `bi
    1. [Installation](#installation)
    1. [Upgrade](#upgrade)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -82,18 +81,13 @@ az bicep upgrade -t 'linux-x64'
 - The [`az bicep` command reference][az bicep]
 - The [Azure CLI]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
+<!-- Upstream -->
 [az bicep]: https://learn.microsoft.com/en-us/cli/azure/bicep
 [what is bicep?]: https://learn.microsoft.com/en-us/azure/azure-resource-manager/bicep/overview
 
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
+<!-- Knowledge base -->
 [azure cli]: cli.md
-
-<!-- external references -->
diff --git a/knowledge base/azure/cli.md b/knowledge base/azure/cli.md
index 42a0612..af2e98b 100644
--- a/knowledge base/azure/cli.md	
+++ b/knowledge base/azure/cli.md	
@@ -520,7 +520,11 @@ All the references in the [further readings] section, plus the following:
 - [`az aks` command reference][az aks reference]
 - [Create and manage Azure Pipelines from the command line]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [authenticate with an azure container registry]: https://learn.microsoft.com/en-us/azure/container-registry/container-registry-authentication?tabs=azure-cli
 [az aks reference]: https://learn.microsoft.com/en-us/cli/azure/aks
 [az reference]: https://learn.microsoft.com/en-us/cli/azure/reference-index
@@ -531,14 +535,14 @@ All the references in the [further readings] section, plus the following:
 [remove a member]: https://learn.microsoft.com/en-us/graph/api/group-delete-members?view=graph-rest-1.0&tabs=http
 [sign in with azure cli]: https://learn.microsoft.com/en-us/cli/azure/authenticate-azure-cli
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [az bicep]: bicep.md#tldr
 [devops]: devops.md
 [devops cli extension]: devops.md#tldr
 [jmespath]: ../jmespath.md
 
-<!-- external references -->
+<!-- Others -->
 [create and manage azure pipelines from the command line]: https://devblogs.microsoft.com/devops/create-and-manage-azure-pipelines-from-the-command-line/
diff --git a/knowledge base/azure/devops.md b/knowledge base/azure/devops.md
index ab54e44..4799b8d 100644
--- a/knowledge base/azure/devops.md	
+++ b/knowledge base/azure/devops.md	
@@ -138,16 +138,20 @@ All the references in the [further readings] section, plus the following:
 
 - [Loops in Azure DevOps Pipelines]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [expressions]: https://learn.microsoft.com/en-us/azure/devops/pipelines/process/expressions
 [use predefined variables]: https://learn.microsoft.com/en-us/azure/devops/pipelines/build/variables
 [az devops]: https://learn.microsoft.com/en-us/cli/azure/devops?view=azure-cli-latest
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [azure cli]: azure%20cli.md
 
-<!-- external references -->
+<!-- Others -->
 [loops in azure devops pipelines]: https://pakstech.com/blog/azure-devops-loops/
diff --git a/knowledge base/azure/kubelogin.md b/knowledge base/azure/kubelogin.md
index 01a1716..d6f0796 100644
--- a/knowledge base/azure/kubelogin.md	
+++ b/knowledge base/azure/kubelogin.md	
@@ -73,12 +73,13 @@ kubelogin remove-tokens
 - [Azure CLI]
 - [`kubectl`][kubectl]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [website]: https://azure.github.io/kubelogin/
 
-<!-- in-article references -->
-<!-- internal references -->
+<!-- Knowledge base -->
 [azure cli]: cli.md
 [kubectl]: ../kubernetes/kubectl.md
-
-<!-- external references -->
diff --git a/knowledge base/gcp/cloud sql.md b/knowledge base/gcp/cloud sql.md
index 46a55c1..613abd5 100644
--- a/knowledge base/gcp/cloud sql.md	
+++ b/knowledge base/gcp/cloud sql.md	
@@ -7,8 +7,6 @@
 1. [Create users in a SQL instance from the MySQL shell](#create-users-in-a-sql-instance-from-the-mysql-shell)
 1. [Use Terraform to manage users in a cloud SQL instance](#use-terraform-to-manage-users-in-a-cloud-sql-instance)
 1. [Gotchas](#gotchas)
-1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -100,17 +98,3 @@ Terraform will use the provider to connect to the proxy and operate on the SQL i
 
 - As of 2021-05-18 the `root` user will **not be able** to create other users from the MySQL shell because it will lack `CREATE USER` permissions.  
 - The documentation says that SQL users created using `gcloud`, the APIs or the cloud console will have the same permissions of the `root` user; in reality, those administrative entities will be able to create users only from the MySQL shell.
-
-## Further readings
-
-## Sources
-
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
-
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
-<!-- external references -->
diff --git a/knowledge base/gcp/config connector.md b/knowledge base/gcp/config connector.md
index 841387b..6af4e8d 100644
--- a/knowledge base/gcp/config connector.md	
+++ b/knowledge base/gcp/config connector.md	
@@ -11,7 +11,6 @@ Provides a collection of Custom Resource Definitions and controllers.
 1. [Resources management](#resources-management)
 1. [Gotchas](#gotchas)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -52,11 +51,11 @@ kubectl get crds --selector cnrm.cloud.google.com/managed-by-kcc=true
 - [Website]
 - [Getting started]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
+<!-- Upstream -->
 [getting started]: https://cloud.google.com/config-connector/docs/how-to/getting-started
 [installation howto]: https://cloud.google.com/config-connector/docs/how-to/install-upgrade-uninstall
 [installation types]: https://cloud.google.com/config-connector/docs/concepts/installation-types
@@ -65,9 +64,3 @@ All the references in the [further readings] section, plus the following:
 [stackdriver]: https://cloud.google.com/stackdriver/docs/solutions/gke
 [website]: https://cloud.google.com/config-connector
 [workload identity]: https://cloud.google.com/kubernetes-engine/docs/how-to/workload-identity
-
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
-<!-- external references -->
diff --git a/knowledge base/gcp/gcloud.md b/knowledge base/gcp/gcloud.md
index 08612db..6e9711a 100644
--- a/knowledge base/gcp/gcloud.md	
+++ b/knowledge base/gcp/gcloud.md	
@@ -59,12 +59,13 @@ All the references in the [further readings] section, plus the following:
 
 - [`gcloud projects`][gcloud projects]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [creating and managing projects]: https://cloud.google.com/resource-manager/docs/creating-managing-projects
 [gcloud projects]: https://cloud.google.com/sdk/gcloud/reference/projects
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
-
-<!-- internal references -->
-<!-- external references -->
diff --git a/knowledge base/gcp/gke.md b/knowledge base/gcp/gke.md
index 13e91c6..3c8f8e2 100644
--- a/knowledge base/gcp/gke.md	
+++ b/knowledge base/gcp/gke.md	
@@ -100,14 +100,17 @@ All the references in the [further readings] section, plus the following:
 - [Connect to a compute instance]
 - [Preparing a Google Kubernetes Engine environment for production]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [connect to a compute instance]: https://cloud.google.com/compute/docs/instances/connecting-to-instance
 [kubectl cluster access]: https://cloud.google.com/kubernetes-engine/docs/how-to/cluster-access-for-kubectl
 [preparing a google kubernetes engine environment for production]: https://cloud.google.com/solutions/prep-kubernetes-engine-for-prod
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
-<!-- external references -->
+<!-- Others -->
 [how to master admission webhooks in kubernetes]: https://digizoo.com.au/1376/mastering-admission-webhooks-in-kubernetes-gke-part-1/
diff --git a/knowledge base/kubernetes/README.md b/knowledge base/kubernetes/README.md
index fdac9cd..f536c69 100644
--- a/knowledge base/kubernetes/README.md	
+++ b/knowledge base/kubernetes/README.md	
@@ -554,6 +554,10 @@ All the references in the [further readings] section, plus the following:
 - [Configuration best practices]
 - [Cloudzero Kubernetes best practices]
 
+<!--
+  References
+  -->
+
 <!-- project's documentation -->
 [addons]: https://kubernetes.io/docs/concepts/cluster-administration/addons/
 [api deprecation policy]: https://kubernetes.io/docs/reference/using-api/deprecation-policy/
@@ -579,11 +583,11 @@ All the references in the [further readings] section, plus the following:
 [using sysctls in a kubernetes cluster]: https://kubernetes.io/docs/tasks/administer-cluster/sysctl-cluster/
 [version skew policy]: https://kubernetes.io/releases/version-skew-policy/
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 [pods]: #pods
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [azure kubernetes service]: ../azure/aks.md
 [create an admission webhook]: ../../examples/kubernetes/create%20an%20admission%20webhook/README.md
 [helm]: helm.md
@@ -595,8 +599,7 @@ All the references in the [further readings] section, plus the following:
 [terraform]: ../terraform.md
 [velero]: velero.md
 
-<!-- external references -->
-
+<!-- Others -->
 [best practices for pod security in azure kubernetes service (aks)]: https://learn.microsoft.com/en-us/azure/aks/developer-best-practices-pod-security
 [build your very own self-hosting platform with raspberry pi and kubernetes]: https://kauri.io/build-your-very-own-self-hosting-platform-with-raspberry-pi-and-kubernetes/5e1c3fdc1add0d0001dff534/c
 [cloudzero kubernetes best practices]: https://www.cloudzero.com/blog/kubernetes-best-practices
diff --git a/knowledge base/kubernetes/helm.md b/knowledge base/kubernetes/helm.md
index 7d7c965..5f780e8 100644
--- a/knowledge base/kubernetes/helm.md	
+++ b/knowledge base/kubernetes/helm.md	
@@ -7,7 +7,6 @@ Package manager for Kubernetes.
 1. [TL;DR](#tldr)
 1. [Start managing existing resources with a specific helm chart](#start-managing-existing-resources-with-a-specific-helm-chart)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -109,18 +108,13 @@ To achieve this:
 - [Kubernetes]
 - [Helmfile]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
+<!-- Upstream -->
 [website]: https://helm.sh/
 
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
+<!-- Knowledge base -->
 [helmfile]: helmfile.md
 [kubernetes]: README.md
-
-<!-- external references -->
diff --git a/knowledge base/kubernetes/helmfile.md b/knowledge base/kubernetes/helmfile.md
index d04b365..3c12adc 100644
--- a/knowledge base/kubernetes/helmfile.md	
+++ b/knowledge base/kubernetes/helmfile.md	
@@ -8,7 +8,6 @@ Leverages `kubectl`.
 
 1. [TL;DR](#tldr)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -32,19 +31,14 @@ helmfile \
 - [`kubectl`][kubectl]
 - [Kubernetes]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
+<!-- Upstream -->
 [github]: https://github.com/helmfile/helmfile
 
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
+<!-- Knowledge base -->
 [helm]: helm.md
 [kubectl]: kubectl.md
 [kubernetes]: README.md
-
-<!-- external references -->
diff --git a/knowledge base/kubernetes/istio.md b/knowledge base/kubernetes/istio.md
index f16b53e..b55aaa5 100644
--- a/knowledge base/kubernetes/istio.md	
+++ b/knowledge base/kubernetes/istio.md	
@@ -77,12 +77,15 @@ All the references in the [further readings] section, plus the following:
 
 - Red Hat's article on [service meshes][service mesh]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [getting started guide]: https://istio.io/latest/docs/setup/getting-started/
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
-<!-- external references -->
+<!-- Others -->
 [service mesh]: https://www.redhat.com/en/topics/microservices/what-is-a-service-mesh
diff --git a/knowledge base/kubernetes/k3s.md b/knowledge base/kubernetes/k3s.md
index 08f347d..451349d 100644
--- a/knowledge base/kubernetes/k3s.md	
+++ b/knowledge base/kubernetes/k3s.md	
@@ -20,16 +20,20 @@ All the references in the [further readings] section, plus the following:
 - The [Build your very own self-hosting platform with Raspberry Pi and Kubernetes] series of articles
 - [Run Kubernetes on a Raspberry Pi with k3s]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [documentation]: https://docs.k3s.io/
 [website]: https://k3s.io/
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [kubernetes]: README.md
 
-<!-- external references -->
+<!-- Others -->
 [build your very own self-hosting platform with raspberry pi and kubernetes]: https://kauri.io/build-your-very-own-self-hosting-platform-with-raspberry-pi-and-kubernetes/5e1c3fdc1add0d0001dff534/c
 [run kubernetes on a raspberry pi with k3s]: https://opensource.com/article/20/3/kubernetes-raspberry-pi-k3s
diff --git a/knowledge base/kubernetes/kapp.md b/knowledge base/kubernetes/kapp.md
index 879ec02..cc7b82c 100644
--- a/knowledge base/kubernetes/kapp.md	
+++ b/knowledge base/kubernetes/kapp.md	
@@ -4,7 +4,6 @@
 
 1. [TL;DR](#tldr)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -24,17 +23,11 @@ $ kapp -y deploy -a 'my-app' -f <(ytt -f './examples/simple-app-example/config-1
 
 ## Further readings
 
-- Official [website]
+- [Website]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
+<!-- Upstream -->
 [website]: https://get-kapp.io
-
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
-<!-- external references -->
diff --git a/knowledge base/kubernetes/keda.md b/knowledge base/kubernetes/keda.md
index 4a5925a..9489e9b 100644
--- a/knowledge base/kubernetes/keda.md	
+++ b/knowledge base/kubernetes/keda.md	
@@ -314,7 +314,11 @@ All the references in the [further readings] section, plus the following:
 - The `/scale` [subresource][/scale subresource]
 - The [ScaledObject specification]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [authentication]: https://keda.sh/docs/2.0/concepts/authentication/
 [concepts]: https://keda.sh/docs/2.0/concepts/
 [external scalers]: https://keda.sh/docs/2.0/concepts/external-scalers/
@@ -324,13 +328,13 @@ All the references in the [further readings] section, plus the following:
 [scaling jobs]: https://keda.sh/docs/2.0/concepts/scaling-jobs/
 [website]: https://keda.sh/
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [kubernetes]: README.md
 
-<!-- external references -->
+<!-- Others -->
 [keda: event driven and serverless containers in kubernetes]: https://www.youtube.com/watch?v=ZK2SS_GXF-g
 [scaledobject specification]: https://github.com/kedacore/keda/blob/v2.0.0/api/v1alpha1/scaledobject_types.go
 [/scale subresource]: https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/#scale-subresource
diff --git a/knowledge base/kubernetes/kubectl.md b/knowledge base/kubernetes/kubectl.md
index d3369c9..46f44ff 100644
--- a/knowledge base/kubernetes/kubectl.md	
+++ b/knowledge base/kubernetes/kubectl.md	
@@ -593,7 +593,11 @@ All the references in the [further readings] section, plus the following:
 - [Run a replicated stateful application]
 - [Accessing an application on Kubernetes in Docker]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [assigning pods to nodes]: https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/
 [cheatsheet]: https://kubernetes.io/docs/reference/kubectl/cheatsheet
 [commands reference]: https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands
@@ -602,14 +606,14 @@ All the references in the [further readings] section, plus the following:
 [enforce pod security standards with namespace labels]: https://kubernetes.io/docs/tasks/configure-pod-container/enforce-standards-namespace-labels/
 [taints and tolerations]: https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration/
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [jsonpath]: ../jsonpath.md
 [kubernetes]: README.md
 
-<!-- external references -->
+<!-- Others -->
 [accessing an application on kubernetes in docker]: https://medium.com/@lizrice/accessing-an-application-on-kubernetes-in-docker-1054d46b64b1
 [run a replicated stateful application]: https://kubernetes.io/docs/tasks/run-application/run-replicated-stateful-application/
 [run a single-instance stateful application]: https://kubernetes.io/docs/tasks/run-application/run-single-instance-stateful-application/
diff --git a/knowledge base/kubernetes/kubeval.md b/knowledge base/kubernetes/kubeval.md
index 1799298..c1c736b 100644
--- a/knowledge base/kubernetes/kubeval.md	
+++ b/knowledge base/kubernetes/kubeval.md	
@@ -22,18 +22,22 @@ Validation failed
 
 ## Sources
 
-- [Validating kubernetes YAML files with kubeval]
-
 All the references in the [further readings] section, plus the following:
 
-<!-- upstream -->
+- [Validating kubernetes YAML files with kubeval]
+
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [kubeval]: https://www.kubeval.com
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [kubernetes]: README.md
 
-<!-- external references -->
+<!-- Others -->
 [validating kubernetes yaml files with kubeval]: https://learnk8s.io/validating-kubernetes-yaml#kubeval
diff --git a/knowledge base/kubernetes/minikube.md b/knowledge base/kubernetes/minikube.md
index bbaab82..0ff7767 100644
--- a/knowledge base/kubernetes/minikube.md	
+++ b/knowledge base/kubernetes/minikube.md	
@@ -95,7 +95,11 @@ All the references in the [further readings] section, plus the following:
 - How to [use local docker images] in Minikube
 - How to [use untrusted certs]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [accessing]: https://minikube.sigs.k8s.io/docs/handbook/accessing
 [completion]: https://minikube.sigs.k8s.io/docs/commands/completion
 [configuration]: https://minikube.sigs.k8s.io/docs/handbook/config
@@ -106,13 +110,13 @@ All the references in the [further readings] section, plus the following:
 [use untrusted certs]: https://minikube.sigs.k8s.io/docs/handbook/untrusted_certs
 [website]: https://minikube.sigs.k8s.io
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [kubectl]: kubectl.md
 [kubernetes]: README.md
 
-<!-- external references -->
+<!-- Others -->
 [hello world]: https://kubernetes.io/docs/tutorials/hello-minikube
 [use local docker images]: https://stackoverflow.com/questions/42564058/how-to-use-local-docker-images-with-minikube#62303945
diff --git a/knowledge base/kubernetes/velero.md b/knowledge base/kubernetes/velero.md
index 747fe9b..723f0c9 100644
--- a/knowledge base/kubernetes/velero.md	
+++ b/knowledge base/kubernetes/velero.md	
@@ -20,16 +20,15 @@ All the references in the [further readings] section, plus the following:
 - [Backup and Restore AKS clusters using Velero]
 
 <!--
-  references
+  References
   -->
 
-<!-- upstream -->
+<!-- Upstream -->
 [documentation]: https://velero.io/docs/main/
 [website]: https://velero.io/
 
-<!-- article sections -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- knowledge base -->
-<!-- others -->
+<!-- Others -->
 [backup and restore aks clusters using velero]: https://github.com/mutazn/Backup-and-Restore-AKS-cluster-using-Velero
diff --git a/knowledge base/mac os x/README.md b/knowledge base/mac os x/README.md
index 4187d64..f9919a0 100644
--- a/knowledge base/mac os x/README.md	
+++ b/knowledge base/mac os x/README.md	
@@ -369,21 +369,25 @@ All the references in the [further readings] section, plus the following:
 - [Resize, rotate, or flip an image in Preview on Mac]
 - [Who is listening on a given TCP port on Mac OS X?]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [compress a pdf in preview on mac]: https://support.apple.com/guide/preview/compress-a-pdf-prvw1509/mac
 [mac startup key combinations]: https://support.apple.com/en-us/HT201255
 [resize, rotate, or flip an image in preview on mac]: https://support.apple.com/guide/preview/resize-rotate-or-flip-an-image-prvw2015/11.0/mac/13.0
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [time machine]: time%20machine.md
 [macports]: macports.md
 [openssl-osx-ca]: openssl-osx-ca.md
 [little snitch]: little%20snitch.md
 
-<!-- external references -->
+<!-- Others -->
 [boot a mac from usb drive]: https://www.wikihow.com/Boot-a-Mac-from-USB-Drive
 [caffeinate your mac]: https://www.theapplegeek.co.uk/blog/caffeinate
 [can touch id for the mac touch bar authenticate sudo users and admin privileges?]: https://apple.stackexchange.com/questions/259093/can-touch-id-for-the-mac-touch-bar-authenticate-sudo-users-and-admin-privileges#306324
diff --git a/knowledge base/mac os x/little snitch.md b/knowledge base/mac os x/little snitch.md
index 1526610..a401a50 100644
--- a/knowledge base/mac os x/little snitch.md	
+++ b/knowledge base/mac os x/little snitch.md	
@@ -2,7 +2,6 @@
 
 1. [TL;DR](#tldr)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -18,15 +17,9 @@ FIXME
 
 - [The .lsrules file format]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
+<!-- Upstream -->
 [the .lsrules file format]: https://help.obdev.at/littlesnitch5/ref-lsrules-file-format
-
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
-<!-- external references -->
diff --git a/knowledge base/mac os x/macports.md b/knowledge base/mac os x/macports.md
index 6a80652..a6bf860 100644
--- a/knowledge base/mac os x/macports.md	
+++ b/knowledge base/mac os x/macports.md	
@@ -148,16 +148,20 @@ All the references in the [further readings] section, plus the following:
 
 - [cheat.sh]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [guide]: https://guide.macports.org/
 [ports]: https://ports.macports.org/
 [website]: https://www.macports.org/
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [mac os x]: README.md
 
-<!-- external references -->
+<!-- Others -->
 [cheat.sh]: https://cheat.sh/port
diff --git a/knowledge base/mac os x/openssl-osx-ca.md b/knowledge base/mac os x/openssl-osx-ca.md
index 6634eb4..74e1ca1 100644
--- a/knowledge base/mac os x/openssl-osx-ca.md	
+++ b/knowledge base/mac os x/openssl-osx-ca.md	
@@ -4,7 +4,6 @@
 
 1. [TL;DR](#tldr)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -29,18 +28,13 @@ find "$(brew --prefix)/etc" -type 'f' -name 'cert.pem' -path '*/openssl*' -exec
 - [Homebrew]
 - [Mac OS X]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
+<!-- Upstream -->
 [github]: https://github.com/raggi/openssl-osx-ca
 
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
+<!-- Knowledge base -->
 [homebrew]: homebrew.md
 [mac os x]: README.md
-
-<!-- external references -->
diff --git a/knowledge base/mac os x/time machine.md b/knowledge base/mac os x/time machine.md
index 5bd5b64..f72624c 100644
--- a/knowledge base/mac os x/time machine.md	
+++ b/knowledge base/mac os x/time machine.md	
@@ -5,7 +5,6 @@
 1. [TL;DR](#tldr)
 1. [Follow logs](#follow-logs)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -29,16 +28,9 @@ sudo tmutil setdestination
 
 - [Mac OS X]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
-
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
+<!-- Knowledge base -->
 [mac os x]: README.md
-
-<!-- external references -->
diff --git a/knowledge base/send an email from cli.md b/knowledge base/send an email from cli.md
index 8f37813..6edf75a 100644
--- a/knowledge base/send an email from cli.md	
+++ b/knowledge base/send an email from cli.md	
@@ -1,5 +1,10 @@
 # Send an email from CLI
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -18,5 +23,10 @@ uuencode file.txt | mail -s "Subject" recipient@mail.server
 - [linux mail command examples]
 - [uuencode]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [linux mail command examples]: https://www.binarytides.com/linux-mail-command-examples
 [uuencode]: https://linux.101hacks.com/unix/uuencode/
diff --git a/knowledge base/set the ondemand cpu governor to not rise the frequencies for niced load.md b/knowledge base/set the ondemand cpu governor to not rise the frequencies for niced load.md
index c2f3ea5..33b411d 100644
--- a/knowledge base/set the ondemand cpu governor to not rise the frequencies for niced load.md	
+++ b/knowledge base/set the ondemand cpu governor to not rise the frequencies for niced load.md	
@@ -1,5 +1,10 @@
 # Set the _ondemand_ CPU governor to not rise the frequencies for niced loads
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -15,6 +20,12 @@ echo "w /sys/devices/system/cpu/cpufreq/ondemand/ignore_nice_load - - - - 1" | s
 - [Cpufreq]
 - [Laptop overheating and battery duration reduction]
 
+<!--
+  References
+  -->
+
+<!-- Knowledge base -->
 [cpufreq]: cpufreq.md
 
+<!-- Others -->
 [laptop overheating and battery duration reduction]: https://wiki.archlinux.org/?title=BOINC#Laptop_overheating_and_battery_duration_reduction
diff --git a/knowledge base/set up port knocking.md b/knowledge base/set up port knocking.md
index c327425..6f44a0b 100644
--- a/knowledge base/set up port knocking.md	
+++ b/knowledge base/set up port knocking.md	
@@ -5,9 +5,11 @@ When the correct sequence is used, the daemon issues a configured command, usual
 
 This is frequently used to open the SSH port in a server for a specific client.
 
-## Further readings
+See [Knockd].
 
-- [Knockd]
+<!--
+  References
+  -->
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [knockd]: knockd.md
diff --git a/knowledge base/shellcheck.md b/knowledge base/shellcheck.md
index cad5528..ac98e5a 100644
--- a/knowledge base/shellcheck.md	
+++ b/knowledge base/shellcheck.md	
@@ -2,6 +2,11 @@
 
 Gives warnings and suggestions about `bash`/`sh` shell scripts.
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -13,5 +18,10 @@ shellcheck /path/to/script.sh
 - [Website]
 - [Github]
 
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [github]: https://github.com/koalaman/shellcheck
 [website]: https://www.shellcheck.net/
diff --git a/knowledge base/snap.md b/knowledge base/snap.md
index b2d4ad4..80d4aa1 100644
--- a/knowledge base/snap.md	
+++ b/knowledge base/snap.md	
@@ -1,5 +1,11 @@
 # Snap
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Manage revisions](#manage-revisions)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -96,5 +102,10 @@ snap list --all \
 - [cheat.sh]
 - [Managing Ubuntu snaps]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [cheat.sh]: https://cheat.sh/snap
 [managing ubuntu snaps]: https://www.freecodecamp.org/news/managing-ubuntu-snaps/
diff --git a/knowledge base/snapper.md b/knowledge base/snapper.md
index a33c5e0..a48f319 100644
--- a/knowledge base/snapper.md	
+++ b/knowledge base/snapper.md	
@@ -1,5 +1,10 @@
 # Snapper
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -44,6 +49,10 @@ snapper modify \
 - [System recovery and snapshot management with Snapper]
 - [Arch Wiki]
 
-<!-- external references -->
+<!--
+  References
+  -->
+
+<!-- Others -->
 [arch wiki]: https://wiki.archlinux.org/title/snapper
 [system recovery and snapshot management with snapper]: https://doc.opensuse.org/documentation/leap/archive/15.0/reference/html/book.opensuse.reference/cha.snapper.html
diff --git a/knowledge base/sort.md b/knowledge base/sort.md
index 21e8d54..91ba2de 100644
--- a/knowledge base/sort.md	
+++ b/knowledge base/sort.md	
@@ -59,9 +59,10 @@ awk 'BEGIN {FS=","; OFS="|"} {print $NF,$0}' file.txt \
 - [Sort a file in Unix based on the last field]
 - [The essential Bash cheat sheet]
 
-<!-- upstream -->
-<!-- in-article references -->
-<!-- internal references -->
-<!-- external references -->
+<!--
+  References
+  -->
+
+<!-- Others -->
 [sort a file in unix based on the last field]: http://www.unixcl.com/2010/11/sort-file-based-on-last-field-unix.html
 [the essential bash cheat sheet]: https://betterprogramming.pub/the-essential-bash-cheat-sheet-e1c3df06560
diff --git a/knowledge base/split.md b/knowledge base/split.md
index 3f0c4b9..11c0929 100644
--- a/knowledge base/split.md	
+++ b/knowledge base/split.md	
@@ -1,5 +1,10 @@
 # Split
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Sources](#sources)
+
 ## TL;DR
 
 ```sh
@@ -18,5 +23,10 @@ split -b 2M -d logs.tgz "logs.tgz."
 - [split large tar into multiple files of certain size]
 - [create a tar archive split into blocks of a maximum size]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [create a tar archive split into blocks of a maximum size]: https://unix.stackexchange.com/questions/61774/create-a-tar-archive-split-into-blocks-of-a-maximum-size
 [split large tar into multiple files of certain size]: https://www.tecmint.com/split-large-tar-into-multiple-files-of-certain-size/
diff --git a/knowledge base/sponge.md b/knowledge base/sponge.md
index 3678b34..4ef17c4 100644
--- a/knowledge base/sponge.md	
+++ b/knowledge base/sponge.md	
@@ -1,5 +1,10 @@
 # Sponge
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -18,5 +23,10 @@ grep -v '^{{#}}' path/to/file | sponge path/to/other/file
 - [mankier man page]
 - [tldr live demo page]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [mankier man page]: https://www.mankier.com/1/sponge
 [tldr live demo page]: https://tldr.ostera.io/sponge
diff --git a/knowledge base/ssh.md b/knowledge base/ssh.md
index cf3a613..b5b295b 100644
--- a/knowledge base/ssh.md	
+++ b/knowledge base/ssh.md	
@@ -1,5 +1,7 @@
 # SSH
 
+## Table of contents <!-- omit in toc -->
+
 1. [TL;DR](#tldr)
 1. [Server installation on Windows](#server-installation-on-windows)
 1. [Key Management](#key-management)
@@ -326,6 +328,8 @@ Solution: update the SSH server.
 
 ## Sources
 
+All the references in the [further readings] section, plus the following:
+
 - [Use SSHFS to mount a remote directory as a volume on OSX]
 - [Using the SSH config file]
 - [How to list keys added to ssh-agent with ssh-add?]
@@ -336,16 +340,23 @@ Solution: update the SSH server.
 - [Get started with OpenSSH for Windows]
 - [Restrict SSH login to a specific IP or host]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [ssh_config man page]: https://man.openbsd.org/ssh_config
 [ssh-agent]: https://www.ssh.com/academy/ssh/agent
 [sshd_config man page]: https://man.openbsd.org/sshd_config
 
-<!-- internal references -->
+<!-- In-article sections -->
+[further readings]: #further-readings
+
+<!-- Files -->
 [ssh_config example]: ../examples/ssh/ssh_config
 [sshd_config example]: ../examples/ssh/sshd_config
 
-<!-- external references -->
+<!-- Others -->
 [get started with openssh for windows]: https://learn.microsoft.com/en-us/windows-server/administration/openssh/openssh_install_firstuse?tabs=gui
 [how to enable ssh access using a gpg key for authentication]: https://opensource.com/article/19/4/gpg-subkeys-ssh
 [how to list keys added to ssh-agent with ssh-add?]: https://unix.stackexchange.com/questions/58969/how-to-list-keys-added-to-ssh-agent-with-ssh-add
diff --git a/knowledge base/stow.md b/knowledge base/stow.md
index 18f9f95..2075517 100644
--- a/knowledge base/stow.md	
+++ b/knowledge base/stow.md	
@@ -1,5 +1,10 @@
 # GNU Stow
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -14,4 +19,9 @@ $ stow --dotfiles --dir $HOME/.dotfiles --target $HOME vim screen --simulate --v
 
 - [Website]
 
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [website]: https://www.gnu.org/software/stow
diff --git a/knowledge base/stunnel.md b/knowledge base/stunnel.md
index 5322a08..0e54bce 100644
--- a/knowledge base/stunnel.md	
+++ b/knowledge base/stunnel.md	
@@ -6,7 +6,6 @@ Proxy designed to add TLS encryption functionality to existing clients and serve
 
 1. [TL;DR](#tldr)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -31,16 +30,10 @@ stunnel 'path/to/config/file'
 - [Website]
 - [Sample configuration for Unix systems]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
+<!-- Upstream -->
 [sample configuration for unix systems]: https://www.stunnel.org/config_unix.html
 [website]: https://www.stunnel.org/
-
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
-<!-- external references -->
diff --git a/knowledge base/sudo.md b/knowledge base/sudo.md
index 4597dc6..4c49754 100644
--- a/knowledge base/sudo.md	
+++ b/knowledge base/sudo.md	
@@ -2,6 +2,17 @@
 
 > Avoid modifying the `sudoers` files manually and execute `visudo` instead; it will check the syntax on save, preventing you from screwing up the file.
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Drop privileges](#drop-privileges)
+1. [Restrict permissions a little](#restrict-permissions-a-little)
+1. [Avoid providing a password](#avoid-providing-a-password)
+1. [Execute commands as a specific user](#execute-commands-as-a-specific-user)
+1. [Troubleshooting](#troubleshooting)
+   1. [I modified a sudoers file manually, messed it up, and now I cannot use sudo anymore](#i-modified-a-sudoers-file-manually-messed-it-up-and-now-i-cannot-use-sudo-anymore)
+1. [Sources](#sources)
+
 ## TL;DR
 
 ```sh
@@ -79,6 +90,11 @@ pkexec visudo -f /etc/sudoers.d/user
 - [sudo as another user with their environment]
 - [sudo: Drop root privileges]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [how to modify an invalid sudoers file]: https://askubuntu.com/questions/73864/how-to-modify-an-invalid-etc-sudoers-file
 [sudo as another user with their environment]: https://unix.stackexchange.com/questions/176997/sudo-as-another-user-with-their-environment
 [sudo: drop root privileges]: https://coderwall.com/p/x2oica/sudo-drop-root-privileges
diff --git a/knowledge base/swap.md b/knowledge base/swap.md
index e1e7aaf..60ee79f 100644
--- a/knowledge base/swap.md	
+++ b/knowledge base/swap.md	
@@ -1,5 +1,12 @@
 # Swap
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Swappiness](#swappiness)
+1. [Swapfile](#swapfile)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -56,6 +63,11 @@ sudo rm /swapfile
 - [How to reload sysctl.conf variables on Linux]
 - [How to empty swap if there is free RAM]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [create a linux swap file]: https://linuxize.com/post/create-a-linux-swap-file/
 [how to reload sysctl.conf variables on linux]: https://www.cyberciti.biz/faq/reload-sysctl-conf-on-linux-using-sysctl/
 [how to empty swap if there is free ram]: https://askubuntu.com/questions/1357/how-to-empty-swap-if-there-is-free-ram#1379
diff --git a/knowledge base/sync.md b/knowledge base/sync.md
index 2f71a80..a5f96fb 100644
--- a/knowledge base/sync.md	
+++ b/knowledge base/sync.md	
@@ -1,5 +1,12 @@
 # Sync
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Sources](#sources)
+
+## TL;DR
+
 ```sh
 # Flush all cached file data of the current user only.
 sync
@@ -33,5 +40,10 @@ sudo sync -f /var/log/syslog
 - [cheat.sh]
 - [Linux sync command]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [cheat.sh]: https://cheat.sh/sync
 [linux sync command]: https://www.computerhope.com/unix/sync.htm
diff --git a/knowledge base/synology dsm.md b/knowledge base/synology dsm.md
index 05e49b8..6b4e94b 100644
--- a/knowledge base/synology dsm.md	
+++ b/knowledge base/synology dsm.md	
@@ -207,19 +207,21 @@ All the references in the [further readings] section, plus the following:
 - [Configuring deduplication block on the Synology]
 - [Encrypting an attached external USB drive?]
 
-<!-- upstream -->
+<!--
+  References
+  -->
 
+<!-- Upstream -->
 [cli administrator guide for synology nas]: https://global.download.synology.com/download/Document/Software/DeveloperGuide/Firmware/DSM/All/enu/Synology_DiskStation_Administration_CLI_Guide.pdf
 [online feature request form]: https://www.synology.com/en-us/form/inquiry/feature
 
-<!-- internal references -->
-
+<!-- In-article sections -->
 [further readings]: #further-readings
 
+<!-- Files -->
 [michelecereda/keybaseio-client]: ../docker/keybaseio-client/README.md
 
-<!-- external references -->
-
+<!-- Others -->
 [configuring deduplication block on the synology]: https://onedrive.live.com/?authkey=%21ACYMJq62iJaU7HY&cid=1E8D74207941B8DD&id=1E8D74207941B8DD%21243&parId=1E8D74207941B8DD%21121&o=OneUp
 [encrypting an attached external usb drive?]: https://www.reddit.com/r/synology/comments/jq4aw6/encrypting_an_attached_external_usb_drive/
 [making disk hibernation work on synology dsm 7]: https://www.reddit.com/r/synology/comments/10cpbqd/making_disk_hibernation_work_on_synology_dsm_7/
diff --git a/knowledge base/sysctl.md b/knowledge base/sysctl.md
index 6cc38b6..6a63d53 100644
--- a/knowledge base/sysctl.md	
+++ b/knowledge base/sysctl.md	
@@ -1,5 +1,12 @@
 # Sysctl
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
+## TL;DR
+
 Default configuration files locations:
 
 1. `/run/sysctl.d/*.conf`
@@ -9,8 +16,6 @@ Default configuration files locations:
 1. `/lib/sysctl.d/*.conf`
 1. `/etc/sysctl.conf`
 
-## TL;DR
-
 ```sh
 # Show the value of a single setting.
 sysctl kernel.ostype
@@ -40,8 +45,12 @@ echo 'vm.swappiness = 5' | sudo tee -a /etc/sysctl.d/99-swappiness.conf
 - [How to reload sysctl.conf variables on Linux]
 - [Documentation for /proc/sys]
 
-<!-- official documentation -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [documentation for /proc/sys]: https://docs.kernel.org/admin-guide/sysctl/
 
-<!-- forums -->
+<!-- Others -->
 [how to reload sysctl.conf variables on linux]: https://www.cyberciti.biz/faq/reload-sysctl-conf-on-linux-using-sysctl/
diff --git a/knowledge base/sysstat.md b/knowledge base/sysstat.md
index 27a37fc..5b8d46f 100644
--- a/knowledge base/sysstat.md	
+++ b/knowledge base/sysstat.md	
@@ -1,9 +1,11 @@
 # sysstat
 
+## Table of contents <!-- omit in toc -->
+
 1. [TL;DR](#tldr)
-2. [Installation example](#installation-example)
-3. [Further readings](#further-readings)
-4. [Sources](#sources)
+1. [Installation example](#installation-example)
+1. [Further readings](#further-readings)
+1. [Sources](#sources)
 
 ## TL;DR
 
@@ -68,5 +70,12 @@ Average:          3      0.19     19.11      0.74      0.00      0.00     79.96
 - [webpage]
 - [github page]
 
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [github page]: https://github.com/sysstat/sysstat
+
+<!-- Others -->
 [webpage]: http://sebastien.godard.pagesperso-orange.fr/
diff --git a/knowledge base/systemd.md b/knowledge base/systemd.md
index 7908e06..088ef7b 100644
--- a/knowledge base/systemd.md	
+++ b/knowledge base/systemd.md	
@@ -1,5 +1,16 @@
 # Systemd
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [User services](#user-services)
+1. [Keep past boots record (persistent logging)](#keep-past-boots-record-persistent-logging)
+1. [Resolved](#resolved)
+   1. [Disable systemd-resolved](#disable-systemd-resolved)
+   1. [Ignore the DNS servers list given by the DHCP server](#ignore-the-dns-servers-list-given-by-the-dhcp-server)
+   1. [Manually set DNS servers](#manually-set-dns-servers)
+1. [Sources](#sources)
+
 ## TL;DR
 
 ```sh
@@ -257,6 +268,11 @@ Restart the `systemd-resolved` service to apply the new settings.
 - [How to Set Hostname Using Hostnamectl Command?]
 - [Suspend and hibernate]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [how to disable systemd-resolved in ubuntu]: https://askubuntu.com/questions/907246/how-to-disable-systemd-resolved-in-ubuntu
 [how to set hostname using hostnamectl command?]: https://linuxhint.com/set-hostname-using-hostnamectl-command/
 [how to set time, timezone and synchronize system clock using timedatectl command]: https://www.tecmint.com/set-time-timezone-and-synchronize-time-using-timedatectl-command/
diff --git a/knowledge base/tar.md b/knowledge base/tar.md
index 2d69b80..0854eb0 100644
--- a/knowledge base/tar.md	
+++ b/knowledge base/tar.md	
@@ -1,5 +1,7 @@
 # Tar
 
+## Table of contents <!-- omit in toc -->
+
 ## TL;DR
 
 ```sh
@@ -33,5 +35,10 @@ short | long              | description
 - [how to compress and extract files using the tar command on linux]
 - [how to create tar gz file in linux using command line]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [how to create tar gz file in linux using command line]: https://www.cyberciti.biz/faq/how-to-create-tar-gz-file-in-linux-using-command-line/
 [how to compress and extract files using the tar command on linux]: https://www.howtogeek.com/248780/how-to-compress-and-extract-files-using-the-tar-command-on-linux/
diff --git a/knowledge base/tcpdump.md b/knowledge base/tcpdump.md
index 8a328be..e033c0e 100644
--- a/knowledge base/tcpdump.md	
+++ b/knowledge base/tcpdump.md	
@@ -1,5 +1,10 @@
 # tcpdump
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Sources](#sources)
+
 ## TL;DR
 
 ```sh
@@ -50,7 +55,9 @@ tcpdump 'tcp[tcpflags] == tcp-fin'
 
 - [A tcpdump tutorial with examples — 50 ways to isolate traffic]
 
-<!-- upstream -->
-<!-- internal references -->
-<!-- external references -->
+<!--
+  References
+  -->
+
+<!-- Others -->
 [a tcpdump tutorial with examples — 50 ways to isolate traffic]: https://danielmiessler.com/study/tcpdump/
diff --git a/knowledge base/terraform enterprise.md b/knowledge base/terraform enterprise.md
index 3180351..89b508d 100644
--- a/knowledge base/terraform enterprise.md	
+++ b/knowledge base/terraform enterprise.md	
@@ -28,14 +28,16 @@ All the references in the [further readings] section, plus the following:
 
 - [Terraform Enterprise documentation]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [terraform enterprise documentation]: https://developer.hashicorp.com/terraform/enterprise
 
-<!-- in-article references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [replicated]: replicated.md
 [tfe-admin]: tfe-admin.md
-
-<!-- external references -->
diff --git a/knowledge base/terraform.md b/knowledge base/terraform.md
index 7f5de9d..92505b1 100644
--- a/knowledge base/terraform.md	
+++ b/knowledge base/terraform.md	
@@ -1,5 +1,7 @@
 # Terraform
 
+## Table of contents <!-- omit in toc -->
+
 1. [TL;DR](#tldr)
 1. [Modules](#modules)
    1. [Useful internal variables](#useful-internal-variables)
@@ -291,11 +293,15 @@ eval "export $(sed -E 's/([[:graph:]]+)[[:blank:]]*=[[:blank:]]*([[:graph:]]+)/T
 
 All the references in the [further readings] section, plus the following:
 
-- [for_each vs count]
+- [`for_each` vs `count`][for_each vs count]
 - [Azure Provider]
 - [Conditional creation of a resource based on a variable in .tfvars]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [cli documentation]: https://www.terraform.io/docs/cli/
 [environment variables]: https://www.terraform.io/cli/config/environment-variables
 [forcing re-creation of resources]: https://www.terraform.io/cli/state/taint
@@ -304,11 +310,10 @@ All the references in the [further readings] section, plus the following:
 [version constraints]: https://www.terraform.io/language/expressions/version-constraints
 [website]: https://www.terraform.io
 
-<!-- internal references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- external references -->
-
+<!-- Others -->
 [azure provider]: https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs
 [conditional creation of a resource based on a variable in .tfvars]: https://stackoverflow.com/questions/60231309/terraform-conditional-creation-of-a-resource-based-on-a-variable-in-tfvars
 [for_each vs count]: https://medium.com/@business_99069/terraform-count-vs-for-each-b7ada2c0b186
diff --git a/knowledge base/tfe-admin.md b/knowledge base/tfe-admin.md
index 9a44263..7eefac0 100644
--- a/knowledge base/tfe-admin.md	
+++ b/knowledge base/tfe-admin.md	
@@ -4,7 +4,6 @@
 
 1. [TL;DR](#tldr)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## TL;DR
 
@@ -20,15 +19,9 @@ tfe-admin health-check
 
 - [Terraform Enterprise]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
+<!-- Knowledge base -->
 [terraform enterprise]: terraform%20enterprise.md
-
-<!-- external references -->
diff --git a/knowledge base/timeout.md b/knowledge base/timeout.md
index 936a8fd..675b124 100644
--- a/knowledge base/timeout.md	
+++ b/knowledge base/timeout.md	
@@ -50,15 +50,14 @@ All the references in the [further readings] section, plus the following:
 - [cheat.sh]
 
 <!--
-  references
+  References
   -->
 
-<!-- upstream -->
+<!-- Upstream -->
 [website]: https://www.gnu.org/software/coreutils/timeout
 
-<!-- article sections -->
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- knowledge base -->
-<!-- others -->
+<!-- Others -->
 [cheat.sh]: https://cheat.sh/timeout
diff --git a/knowledge base/tldr.md b/knowledge base/tldr.md
index db0b87d..2347621 100644
--- a/knowledge base/tldr.md	
+++ b/knowledge base/tldr.md	
@@ -1,5 +1,11 @@
 # TL;DR
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr-1)
+1. [Further readings](#further-readings)
+
+## TL;DR
 ```sh
 pip3 install tldr                   # official python client
 brew install tealdeer               # rust client
@@ -12,6 +18,11 @@ sudo port install tldr-cpp-client   # c++ client
 - [live demo]
 - project's [github] page
 
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [github]: https://github.com/tldr-pages/tldr
 [live demo]: https://tldr.ostera.io
 [website]: https://tldr.sh/
diff --git a/knowledge base/toolbox.md b/knowledge base/toolbox.md
index 72e7b03..4e8f1e5 100644
--- a/knowledge base/toolbox.md	
+++ b/knowledge base/toolbox.md	
@@ -2,6 +2,12 @@
 
 Runs on top of [Podman].
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+1. [Sources](#sources)
+
 ## TL;DR
 
 ```sh
@@ -37,12 +43,17 @@ toolbox rmi -af
 - [GitHub] page
 - [Podman]
 
-[podman]: podman.md
-
-[github]: https://github.com/containers/toolbox
-
 ## Sources
 
 - [Fedora Silverblue]
 
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [fedora silverblue]: https://docs.fedoraproject.org/en-US/fedora-silverblue/toolbox/
+[github]: https://github.com/containers/toolbox
+
+<!-- Knowledge base -->
+[podman]: podman.md
diff --git a/knowledge base/touch.md b/knowledge base/touch.md
index 9e8778f..ec623ab 100644
--- a/knowledge base/touch.md	
+++ b/knowledge base/touch.md	
@@ -1,4 +1,6 @@
-# Touch
+# The `touch` command
+
+## Table of contents <!-- omit in toc -->
 
 1. [TL;DR](#tldr)
 
diff --git a/knowledge base/trap.md b/knowledge base/trap.md
index f327c99..fa1e1eb 100644
--- a/knowledge base/trap.md	
+++ b/knowledge base/trap.md	
@@ -1,4 +1,9 @@
-# Trap
+# The Bash `trap` command
+
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Sources](#sources)
 
 ## TL;DR
 
@@ -19,5 +24,10 @@ trap - SIGINT
 - [Using Bash traps in your scripts]
 - [The Bash trap command]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [the bash trap command]: https://www.linuxjournal.com/content/bash-trap-command
 [using bash traps in your scripts]: https://opensource.com/article/20/6/bash-trap
diff --git a/knowledge base/truncate.md b/knowledge base/truncate.md
index 0102f1b..f65195c 100644
--- a/knowledge base/truncate.md	
+++ b/knowledge base/truncate.md	
@@ -1,7 +1,13 @@
-# truncate
+# The `truncate` command
 
 Shrink or extend the size of a file to the specified size.
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+1. [Sources](#sources)
+
 ## TL;DR
 
 ```sh
@@ -34,6 +40,12 @@ truncate --no-create --size 0 'file'
 
 - [cheat.sh]
 
-<!-- -->
-[cheat.sh]: https://cheat.sh/truncate
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [gnu's documentation]: https://www.gnu.org/software/coreutils/truncate
+
+<!-- Others -->
+[cheat.sh]: https://cheat.sh/truncate
diff --git a/knowledge base/turris omnia.md b/knowledge base/turris omnia.md
index 6614121..ab38161 100644
--- a/knowledge base/turris omnia.md	
+++ b/knowledge base/turris omnia.md	
@@ -5,7 +5,6 @@
 1. [Factory reset](#factory-reset)
 1. [Hardware upgrades](#hardware-upgrades)
 1. [Further readings](#further-readings)
-1. [Sources](#sources)
 
 ## Factory reset
 
@@ -47,18 +46,17 @@ Most compatible upgrades are available on [Discomp].
 
 - [Turris OS]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
+<!-- Upstream -->
 [supported sfp modules]: https://wiki.turris.cz/doc/en/public/sfp
 
-<!-- internal references -->
-[further readings]: #further-readings
+<!-- Knowledge base -->
 [turris os]: turris%20os.md
 
-<!-- external references -->
+<!-- Others -->
 [discomp]: https://www.discomp.cz/
 [kingston 1024g ssd kc600 sata3 msata]: https://www.amazon.com/gp/product/B08ZNRTDD8/
 [turris omnia wifi 6 upgrade kit]: https://www.discomp.cz/turris-omnia-wi-fi-6-upgrade-kit_d120048.html
diff --git a/knowledge base/turris os.md b/knowledge base/turris os.md
index 44e4999..4e0ba4e 100644
--- a/knowledge base/turris os.md	
+++ b/knowledge base/turris os.md	
@@ -469,7 +469,11 @@ All the references in the [further readings] section, plus the following:
 - [Pi-Hole on Turris Omnia]
 - [Installing pi-hole on Turris Omnia]
 
-<!-- project's references-->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [docs]: https://docs.turris.cz
 [factory reset on turris omnia]: https://docs.turris.cz/hw/omnia/rescue-modes/
 [home nas]: https://wiki.turris.cz/doc/en/howto/nas
@@ -478,15 +482,17 @@ All the references in the [further readings] section, plus the following:
 [turris wiki]: https://wiki.turris.cz/doc/en/start
 [website]: https://www.turris.com/turris-os/
 
-<!-- internal references -->
+<!-- In-article sections -->
 [further readings]: #further-readings
+
+<!-- Knowledge base -->
 [lxc]: lxc.md
 [opkg]: opkg.md
 [pi-hole]: pi-hole.md
 [ssh]: ssh.md
 [uci]: uci.md
 
-<!-- external references -->
+<!-- Others -->
 [install pi-hole]: https://github.com/nminten/turris-omnia_documentation/blob/master/howtos/pihole.md
 [installing pi-hole on turris omnia]: https://blog.weinreich.org/posts/2020/2020-05-02-turris-omnia-pihole/
 [openwrt uci]: https://openwrt.org/docs/guide-user/base-system/uci
diff --git a/knowledge base/ubports.md b/knowledge base/ubports.md
index 46fcb06..70f0086 100644
--- a/knowledge base/ubports.md	
+++ b/knowledge base/ubports.md	
@@ -1,5 +1,7 @@
 # UBports
 
+## Table of contents <!-- omit in toc -->
+
 1. [TL;DR](#tldr)
 1. [Connect using SSH](#connect-using-ssh)
 1. [Sources](#sources)
@@ -85,5 +87,9 @@ libertine-container-manager destroy -i 'identifier'
 
 - [Documentation]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [documentation]: https://docs.ubports.com/en/latest/index.html
diff --git a/knowledge base/uci.md b/knowledge base/uci.md
index a348394..e66e30e 100644
--- a/knowledge base/uci.md	
+++ b/knowledge base/uci.md	
@@ -1,7 +1,13 @@
-# uci
+# The `uci` command
 
 Command line utility for OpenWrt's UCI system.
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+1. [Sources](#sources)
+
 ## TL;DR
 
 ```sh
@@ -48,10 +54,12 @@ reload_config
 - [The UCI system]
 - [Turris Omnia]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [the uci system]: https://openwrt.org/docs/guide-user/base-system/uci
 
-<!-- internal references -->
+<!-- Knowledge base -->
 [Turris Omnia]: turris.md
-
-<!-- external references -->
diff --git a/knowledge base/uniq.md b/knowledge base/uniq.md
index c76a6cb..a0c9205 100644
--- a/knowledge base/uniq.md	
+++ b/knowledge base/uniq.md	
@@ -1,4 +1,9 @@
-# Uniq
+# The `uniq` command
+
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Sources](#sources)
 
 ## TL;DR
 
@@ -23,8 +28,9 @@ uniq -cd path/to/file
 
 - [The essential Bash cheat sheet]
 
-<!-- upstream -->
-<!-- in-article references -->
-<!-- internal references -->
-<!-- external references -->
+<!--
+  References
+  -->
+
+<!-- Others -->
 [the essential bash cheat sheet]: https://betterprogramming.pub/the-essential-bash-cheat-sheet-e1c3df06560
diff --git a/knowledge base/upgrade a ps4's hdd/README.md b/knowledge base/upgrade a ps4's hdd/README.md
index adf2fbf..e0c5dcd 100644
--- a/knowledge base/upgrade a ps4's hdd/README.md	
+++ b/knowledge base/upgrade a ps4's hdd/README.md	
@@ -87,23 +87,18 @@ Please note, users who have never signed in to PlayStation™Network (PSN) can r
 - [PS4: External hard drive support]
 - [How to back up and restore PS4 console data]
 
-## Sources
+<!--
+  References
+  -->
 
-All the references in the [further readings] section, plus the following:
-
-<!-- upstream -->
+<!-- Upstream -->
 [how to back up and restore ps4 console data]: https://www.playstation.com/en-us/support/hardware/ps4-back-up-and-restore-with-external-storage/
 [ps4: external hard drive support]: https://www.playstation.com/en-us/support/hardware/ps4-external-hdd-support/
 [ps4: upgrade hdd]: https://www.playstation.com/en-us/support/hardware/ps4-upgrade-hdd/#7000
 [system software download page]: https://www.playstation.com/en-us/support/hardware/ps4/system-software/
 
-<!-- in-article references -->
-[further readings]: #further-readings
-
-<!-- internal references -->
+<!-- In-article sections -->
 [back up the existing data on an external usb storage device]: #back-up-the-existing-data-on-an-external-usb-storage-device
 [reinstall the system software]: #reinstall-the-system-software
 [restore backed up data from an external usb storage device to the playstation 4]: #restore-backed-up-data-from-an-external-usb-storage-device-to-the-playstation-4
 [upgrade the hdd]: #upgrade-the-hdd
-
-<!-- external references -->
diff --git a/knowledge base/useradd.md b/knowledge base/useradd.md
index 369c807..77e8d74 100644
--- a/knowledge base/useradd.md	
+++ b/knowledge base/useradd.md	
@@ -1,6 +1,11 @@
-# Useradd
+# The `useradd` command
 
-Create a new user.
+Creates new users.
+
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Sources](#sources)
 
 ## TL;DR
 
@@ -36,4 +41,9 @@ sudo useradd --system username
 
 - [cheat.sh]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [cheat.sh]: cheat.sh/useradd
diff --git a/knowledge base/userdel.md b/knowledge base/userdel.md
index 035066e..a9a524c 100644
--- a/knowledge base/userdel.md	
+++ b/knowledge base/userdel.md	
@@ -1,6 +1,11 @@
-# Useradd
+# The `useradd` command
 
-Delete a user account and its related files.
+Delete users accounts and their related files.
+
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Sources](#sources)
 
 ## TL;DR
 
@@ -19,4 +24,9 @@ sudo userdel --remove username
 
 - [cheat.sh]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [cheat.sh]: cheat.sh/userdel
diff --git a/knowledge base/usermod.md b/knowledge base/usermod.md
index 214aa64..6f8dc66 100644
--- a/knowledge base/usermod.md	
+++ b/knowledge base/usermod.md	
@@ -1,4 +1,9 @@
-# Usermod
+# The `usermod` command
+
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Sources](#sources)
 
 ## TL;DR
 
@@ -35,4 +40,9 @@ sudo usermod --move-home --home path/to/new_home lonny
 
 - [cheat.sh]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [cheat.sh]: cheat.sh/usermod
diff --git a/knowledge base/vagrant.md b/knowledge base/vagrant.md
index 5855b98..0c4836b 100644
--- a/knowledge base/vagrant.md	
+++ b/knowledge base/vagrant.md	
@@ -1,5 +1,7 @@
 # Vagrant
 
+## Table of contents <!-- omit in toc -->
+
 1. [TL;DR](#tldr)
 1. [Usage](#usage)
    1. [Boxes management](#boxes-management)
@@ -227,12 +229,16 @@ end
 - [How do I reboot a Vagrant guest from a provisioner?]
 - [Configuring Vagrant virtual machines with .env]
 
-<!-- upstream -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [getting started]: https://learn.hashicorp.com/tutorials/vagrant/getting-started-index
 [multi-machine]: https://www.vagrantup.com/docs/multi-machine
 [tips & tricks]: https://www.vagrantup.com/docs/vagrantfile/tips
 
-<!-- external references -->
+<!-- Others -->
 [configuring vagrant virtual machines with .env]: https://www.nickhammond.com/configuring-vagrant-virtual-machines-with-env/
 [how do i reboot a vagrant guest from a provisioner?]: https://superuser.com/questions/1338429/how-do-i-reboot-a-vagrant-guest-from-a-provisioner#1579326
 [how to set vagrant virtualbox video memory]: https://stackoverflow.com/questions/24231620/how-to-set-vagrant-virtualbox-video-memory#24253435
diff --git a/knowledge base/vault.md b/knowledge base/vault.md
index 2351b21..2f6926b 100644
--- a/knowledge base/vault.md	
+++ b/knowledge base/vault.md	
@@ -1,5 +1,10 @@
 # Hashicorp Vault
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -35,5 +40,9 @@ vault read -format 'json' 'secret/data/demo-app/config'
 
 - [HashiCorp Vault]
 
-<!-- -->
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [hashicorp vault]: https://www.vaultproject.io/
diff --git a/knowledge base/vboxmanage.md b/knowledge base/vboxmanage.md
index 183673d..3af4c69 100644
--- a/knowledge base/vboxmanage.md	
+++ b/knowledge base/vboxmanage.md	
@@ -1,5 +1,9 @@
 # VBoxManage
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+
 ## TL;DR
 
 ```sh
diff --git a/knowledge base/vim.md b/knowledge base/vim.md
index ed686d0..c46d9f9 100644
--- a/knowledge base/vim.md	
+++ b/knowledge base/vim.md	
@@ -1,5 +1,11 @@
 # Vim
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Modelines](#modelines)
+1. [Sources](#sources)
+
 ## TL;DR
 
 ```sh
@@ -67,6 +73,11 @@ Examples:
 - [Basic vimrc]
 - [Set whitespace preferences by filetype]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [basic vimrc]: https://github.com/amix/vimrc/blob/master/vimrcs/basic.vim
 [embed vim settings in file]: https://stackoverflow.com/questions/3958416/embed-vim-settings-in-file#3958516
 [modeline magic]: https://vim.fandom.com/wiki/Modeline_magic
diff --git a/knowledge base/vivaldi.md b/knowledge base/vivaldi.md
index 1fedde7..3cfe2e5 100644
--- a/knowledge base/vivaldi.md	
+++ b/knowledge base/vivaldi.md	
@@ -1,5 +1,10 @@
 # Vivaldi browser
 
+## Table of contents <!-- omit in toc -->
+
+1. [Network activity](#network-activity)
+1. [Further readings](#further-readings)
+
 ## Network activity
 
 | URL                 | Ports      | Description                 |
diff --git a/knowledge base/xargs.md b/knowledge base/xargs.md
index d69dca0..1989384 100644
--- a/knowledge base/xargs.md	
+++ b/knowledge base/xargs.md	
@@ -1,5 +1,9 @@
 # `xargs`
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+
 ## TL;DR
 
 ```sh
diff --git a/knowledge base/xclip.md b/knowledge base/xclip.md
index 59a41d8..77bf758 100644
--- a/knowledge base/xclip.md	
+++ b/knowledge base/xclip.md	
@@ -1,5 +1,10 @@
 # Xclip
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Sources](#sources)
+
 ## TL;DR
 
 ```sh
@@ -8,7 +13,7 @@ xclip -selection clipboard < file
 
 ## Sources
 
-- [copy the contents of a file into the clipboard without displaying its contents]
+- [Copy the contents of a file into the clipboard without displaying its contents]
 
 <!--
   References
diff --git a/knowledge base/yaml.md b/knowledge base/yaml.md
index 339f4da..21efc63 100644
--- a/knowledge base/yaml.md	
+++ b/knowledge base/yaml.md	
@@ -1,5 +1,10 @@
 # YAML
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```yaml
@@ -22,7 +27,14 @@ object:
 ## Further readings
 
 - [yaml-multiline.info]
-- [yamllint]
+- [`yamllint`][yamllint]
 
-[yaml-multiline.info]: https://yaml-multiline.info
+<!--
+  References
+  -->
+
+<!-- Knowledge base -->
 [yamllint]: yamllint.md
+
+<!-- Others -->
+[yaml-multiline.info]: https://yaml-multiline.info
diff --git a/knowledge base/yamllint.md b/knowledge base/yamllint.md
index 2de2af2..dd63820 100644
--- a/knowledge base/yamllint.md	
+++ b/knowledge base/yamllint.md	
@@ -2,6 +2,12 @@
 
 A linter for YAML files written in Python and compatible with Python 3 only.
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Configuration](#configuration)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -54,6 +60,11 @@ extends: relaxed
 - Yamllint's [documentation]
 - [Rules]
 
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [documentation]: https://yamllint.readthedocs.io/en/stable
 [github]: https://github.com/adrienverge/yamllint
 [rules]: https://yamllint.readthedocs.io/en/stable/rules.html
diff --git a/knowledge base/youtube-dl.md b/knowledge base/youtube-dl.md
index cd29852..8a4b9ef 100644
--- a/knowledge base/youtube-dl.md	
+++ b/knowledge base/youtube-dl.md	
@@ -2,6 +2,13 @@
 
 > Not deprecated, but surpassed many times by its improved fork, [yt-dlp].
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Installation](#installation)
+1. [Further readings](#further-readings)
+1. [Sources](#sources)
+
 ## TL;DR
 
 ```sh
@@ -80,9 +87,17 @@ Alternatively, most package managers will have the package available.
 - [Youtube-DL tutorial with examples for beginners]
 - [using youtube-dl to download entire youtube channel]
 
+<!--
+  References
+  -->
+
+<!-- Upstream -->
 [project]: https://github.com/ytdl-org/youtube-dl
 [website]: http://ytdl-org.gitlab.io/youtube-dl
+
+<!-- Knowledge base -->
 [yt-dlp]: yt-dlp.md
 
+<!-- Others -->
 [youtube-dl tutorial with examples for beginners]: https://ostechnix.com/youtube-dl-tutorial-with-examples-for-beginners
 [using youtube-dl to download entire youtube channel]: https://askubuntu.com/questions/856911/using-youtube-dl-to-download-entire-youtube-channel#1245829
diff --git a/knowledge base/yt-dlp.md b/knowledge base/yt-dlp.md
index ec12761..328fca3 100644
--- a/knowledge base/yt-dlp.md	
+++ b/knowledge base/yt-dlp.md	
@@ -2,6 +2,11 @@
 
 Improved fork of [youtube-dl].
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 > To be able to merge multiple formats into one, you will also need to install `ffmpeg`.
@@ -49,6 +54,12 @@ yt-dlp -ciw \
 - [GitHub]
 - [youtube-dl]
 
-[youtube-dl]: youtube-dl.md
+<!--
+  References
+  -->
 
+<!-- Upstream -->
 [github]: https://github.com/yt-dlp/yt-dlp
+
+<!-- Knowledge base -->
+[youtube-dl]: youtube-dl.md
diff --git a/knowledge base/zfs.md b/knowledge base/zfs.md
index 8576543..8ca1c92 100644
--- a/knowledge base/zfs.md	
+++ b/knowledge base/zfs.md	
@@ -281,17 +281,18 @@ All the references in the [further readings] section, plus the following:
 - [How to Enable ZFS Deduplication]
 - [ZFS support + kernel, best approach]
 
-<!-- upstream -->
+<!--
+  References
+  -->
 
+<!-- Upstream -->
 [openzfs docs]: https://openzfs.github.io/openzfs-docs/
 [oracle solaris zfs administration guide]: https://docs.oracle.com/cd/E19253-01/819-5461/index.html
 
-<!-- internal references -->
-
+<!-- In-article sections -->
 [further readings]: #further-readings
 
-<!-- external references -->
-
+<!-- Others -->
 [aaron toponce's article on zfs administration]: https://pthree.org/2012/12/04/zfs-administration-part-i-vdevs/
 [archlinux wiki]: https://wiki.archlinux.org/title/ZFS
 [article on zfs on linux]: https://blog.heckel.io/2017/01/08/zfs-encryption-openzfs-zfs-on-linux
diff --git a/knowledge base/zip.md b/knowledge base/zip.md
index e1ab31e..f847cd8 100644
--- a/knowledge base/zip.md	
+++ b/knowledge base/zip.md	
@@ -1,5 +1,10 @@
 # Zip
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -17,4 +22,9 @@ unzip -Zl foo.zip
 
 - [cheat.sh]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [cheat.sh]: https://cheat.sh/zip
diff --git a/knowledge base/zsh.md b/knowledge base/zsh.md
index c812bef..a2320c9 100644
--- a/knowledge base/zsh.md	
+++ b/knowledge base/zsh.md	
@@ -1,5 +1,7 @@
 # ZSH
 
+## Table of contents <!-- omit in toc -->
+
 1. [TL;DR](#tldr)
 1. [Alias expansion](#alias-expansion)
 1. [Parameter expansion](#parameter-expansion)
@@ -578,6 +580,11 @@ compaudit | xargs chmod g-w
 - [Handling Signals With Trap]
 - [Upper- or lower-casing strings]
 
+<!--
+  References
+  -->
+
+<!-- Others -->
 [antibody]: https://github.com/getantibody/antibody
 [antidote]: https://getantidote.github.io/
 [antigen]: https://github.com/zsh-users/antigen
@@ -589,7 +596,6 @@ compaudit | xargs chmod g-w
 [zsh-completions]: https://github.com/zsh-users/zsh-completions
 [zsh-history-substring-search]: https://github.com/zsh-users/zsh-history-substring-search
 [zsh-syntax-highlighting]: https://github.com/zsh-users/zsh-syntax-highlighting
-
 [awesome zsh plugins]: https://github.com/unixorn/awesome-zsh-plugins
 [completion config example]: https://github.com/ThiefMaster/zsh-config/blob/master/zshrc.d/completion.zsh
 [fix key settings (home/end/insert/delete) in .zshrc when running zsh in terminator terminal emulator]: https://stackoverflow.com/questions/8638012/fix-key-settings-home-end-insert-delete-in-zshrc-when-running-zsh-in-terminat#8645267
diff --git a/knowledge base/zstd.md b/knowledge base/zstd.md
index 2d8e6ed..83d945f 100644
--- a/knowledge base/zstd.md	
+++ b/knowledge base/zstd.md	
@@ -2,6 +2,10 @@
 
 The `zstd`, `zstdmt`, `unzstd`, `zstdcat` utilities compress or decompress `.zst` files.
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+
 ## TL;DR
 
 ```sh
diff --git a/knowledge base/zypper.md b/knowledge base/zypper.md
index 92c198b..a17c186 100644
--- a/knowledge base/zypper.md	
+++ b/knowledge base/zypper.md	
@@ -2,6 +2,12 @@
 
 SUSE and openSUSE GNU/Linux's package management utility.
 
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Gotchas](#gotchas)
+1. [Further readings](#further-readings)
+
 ## TL;DR
 
 ```sh
@@ -28,6 +34,12 @@ sudo rpm --query --list ${PACKAGE_NAME}
 - [rpm]
 - [How can I list all files which have been installed by an ZYpp/Zypper package?]
 
+<!--
+  References
+  -->
+
+<!-- Knowledge base -->
 [rpm]: rpm.md
 
+<!-- Others -->
 [how can i list all files which have been installed by an zypp/zypper package?]: https://unix.stackexchange.com/questions/162092/how-can-i-list-all-files-which-have-been-installed-by-an-zypp-zypper-package#239944