diff --git a/ansible/README.md b/ansible/README.md
index 2b5f5e2..9f44126 100644
--- a/ansible/README.md
+++ b/ansible/README.md
@@ -18,3 +18,4 @@
 1. community.general.snap module. https://docs.ansible.com/ansible/latest/collections/community/general/snap_module.html.
 1. Ansible remote_user vs ansible_user. https://stackoverflow.com/a/36677811.
 1. ansible.builtin.service module. https://docs.ansible.com/ansible/latest/collections/ansible/builtin/service_module.html.
+1. Ansible variables. https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_variables.html.