Added JAR paper by Wenzel and Wiedijk.

--- a/src/HOL/Extraction/document/root.bib	Tue Nov 13 11:02:55 2007 +0100
+++ b/src/HOL/Extraction/document/root.bib	Tue Nov 13 11:04:30 2007 +0100
@@ -27,3 +27,13 @@
   series = 	 {Electronic Notes in Theoretical Computer Science},
   publisher =	 {Elsevier Science Publishers}
 }
+
+@Article{Wenzel-Wiedijk-JAR2002,
+  author = 	 {Markus Wenzel and Freek Wiedijk},
+  title = 	 {A comparison of the mathematical proof languages {M}izar and {I}sar},
+  journal = 	 {Journal of Automated Reasoning},
+  year = 	 2002,
+  volume =	 29,
+  number =	 {3-4},
+  pages =	 {389-411}
+}