--- a/src/HOL/Isar_Examples/Mutilated_Checkerboard.thy Thu Dec 02 16:52:52 2010 +0100
+++ b/src/HOL/Isar_Examples/Mutilated_Checkerboard.thy Thu Dec 02 17:20:34 2010 +0100
@@ -10,9 +10,7 @@
begin
text {* The Mutilated Checker Board Problem, formalized inductively.
- See \cite{paulson-mutilated-board} and
- \url{http://isabelle.in.tum.de/library/HOL/Induct/Mutil.html} for
- the original tactic script version. *}
+ See \cite{paulson-mutilated-board} for the original tactic script version. *}
subsection {* Tilings *}