diff --git a/ruby/expect-a-method-to-be-called-and-actually-call-it.md b/ruby/expect-a-method-to-be-called-and-actually-call-it.md
index 1a656aa..25b2f14 100644
--- a/ruby/expect-a-method-to-be-called-and-actually-call-it.md
+++ b/ruby/expect-a-method-to-be-called-and-actually-call-it.md
@@ -40,3 +40,5 @@ describe "expect and call original" do
   end
 end
 ```
+
+[source](https://relishapp.com/rspec/rspec-mocks/v/2-14/docs/message-expectations/calling-the-original-method)