diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 589197c9..e8f81ba4 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -95,3 +95,5 @@ like this:
 Resolves: #123
 See also: #456, #789
 ```
+
+Source: [Tim Pope](https://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html)'s article.