diff --git a/scribble_to_epub/assets/scribblehub.css b/scribble_to_epub/assets/scribblehub.css
index 417ca17..cb0351f 100644
--- a/scribble_to_epub/assets/scribblehub.css
+++ b/scribble_to_epub/assets/scribblehub.css
@@ -1,3 +1,4 @@
+/* https://github.com/agmlego/py-scribblehub-to-epub/blob/trunk/py_scribblehub_to_epub/assets/scribblehub.css */
 .epub-author {
   color: #555;
 }