diff -r b7ae269c0d68 -r 332cd0197d34 src/Pure/Concurrent/future.ML
--- a/src/Pure/Concurrent/future.ML	Wed Jul 21 21:08:40 2010 +0200
+++ b/src/Pure/Concurrent/future.ML	Thu Jul 22 10:41:12 2010 +0200
@@ -3,6 +3,7 @@
 
 Future values, see also
 http://www4.in.tum.de/~wenzelm/papers/parallel-isabelle.pdf
+http://www4.in.tum.de/~wenzelm/papers/parallel-ml.pdf
 
 Notes: