diff -r 08f59175e541 -r 3eb0694e6fcb doc-src/IsarImplementation/Thy/Logic.thy
--- a/doc-src/IsarImplementation/Thy/Logic.thy	Mon Oct 11 21:05:01 2010 +0100
+++ b/doc-src/IsarImplementation/Thy/Logic.thy	Mon Oct 11 21:10:50 2010 +0100
@@ -619,7 +619,7 @@
   "d(\<alpha>\<^isub>i)"} for some @{text "\<alpha>\<^isub>i"} projected from @{text
   "\<^vec>\<alpha>"}.  Thus overloaded definitions essentially work by
   primitive recursion over the syntactic structure of a single type
-  argument.
+  argument.  See also \cite[\S4.3]{Haftmann-Wenzel:2006:classes}.
 *}
 
 text %mlref {*