Fix link to the K&R C book

Fixes #512.

diff --git a/doc/CONTRIBUTING.md b/doc/CONTRIBUTING.md
index 54407a50108f941fb3d9ca2ad989bb67681fa6be..acfe41df9a795195502fbc30ae3b94673644dadc 100644 (file)
--- a/doc/CONTRIBUTING.md
+++ b/doc/CONTRIBUTING.md
@@ -17,7 +17,7 @@ I follow the [Linux Coding Style][4] with the following variations:
 - [Indent with tabs, align with spaces][5].
 - Always use braces when using control structures.
 
-[1]: http://cm.bell-labs.com/cm/cs/cbook/
+[1]: https://www.bell-labs.com/usr/dmr/www/cbook/
 [2]: http://www.x.org/releases/X11R7.5/doc/libxcb/tutorial/
 [3]: http://git-scm.com/documentation
 [4]: http://www.kernel.org/doc/Documentation/CodingStyle