diff --git a/free-programming-books.md b/free-programming-books.md
index ceefbe60934801bf06cb16f06817ba5eafef6e07..4af0802715666f55c96b05fbd1fd8f71a534111e 100644
--- a/free-programming-books.md
+++ b/free-programming-books.md
@@ -2665,5 +2665,5 @@ Kerridge (PDF) (email address *requested*, not required)
 ### xBase (dBase / Clipper / Harbour)
 
 * [Application Development with Harbour](https://en.wikibooks.org/wiki/Application_Development_with_Harbour) - Wikibooks
-* [CA-Clipper 5.2 Norton Guide](http://www.ousob.com/ng/clguide/)
+* [CA-Clipper 5.2 Norton Guide](https://web.archive.org/web/20190516192814/http://www.ousob.com/ng/clguide/)
 * [Clipper Tutorial: a Guide to Open Source Clipper(s)](https://en.wikibooks.org/wiki/Clipper_Tutorial%3A_a_Guide_to_Open_Source_Clipper(s)) - Wikibooks