diff --git a/doc/examples/progress_bar.py b/doc/examples/progress_bar.py
index a3032db30..9a0a689f5 100644
--- a/doc/examples/progress_bar.py
+++ b/doc/examples/progress_bar.py
@@ -8,6 +8,8 @@ This script will demonstrate how to implement a simple
 progress bar for a Ray actor to track progress across various
 different distributed components.
 
+Original source: `Link <https://github.com/votingworks/arlo-e2e>`_
+
 Setup: Dependencies
 -------------------