diff --git a/gists/let-lambda.el b/gists/let-lambda.el
index ed814a5..f49aa6b 100644
--- a/gists/let-lambda.el
+++ b/gists/let-lambda.el
@@ -1,3 +1,5 @@
+;; https://stackoverflow.com/questions/36039840/elisp-bind-a-lambda-in-a-let-and-execute-it
+
 (let ((f (lambda (s) (message s))))
   ;; f is a variable so should be treated as such.
   (funcall f "This works.")