diff --git a/defaults/README.md b/defaults/README.md
index a969456..3affdc7 100644
--- a/defaults/README.md
+++ b/defaults/README.md
@@ -3,3 +3,5 @@
 The default variable definitions of the Ansible role.
 
 Variables defined here can be overrided by the role consumers, which can be used to customize the role's behaviors.
+
+Refer to the [Using Variables — Ansible Community Documentation](https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_variables.html) official documentation for more details.