diff -r 73a415af3bcd -r 61bd5d99c3ab prio/Paper/Paper.thy
--- a/prio/Paper/Paper.thy	Tue Apr 17 15:45:05 2012 +0000
+++ b/prio/Paper/Paper.thy	Tue Apr 17 15:55:37 2012 +0000
@@ -1287,7 +1287,12 @@
   definitions and proofs span over 770 lines of code. The properties relevant
   for an implementation require 2000 lines. The code of our formalisation 
   can be downloaded from
-  \url{http://www.inf.kcl.ac.uk/staff/urbanc/pip.html}.
+  \url{http://www.inf.kcl.ac.uk/staff/urbanc/pip.html}.\medskip
+
+  \noindent
+  {\bf Acknowledgements:}
+  We are grateful for the comments we received from anonymous
+  referees.
 
   \bibliographystyle{plain}
   \bibliography{root}