CONTRIBUTORS

--- a/CONTRIBUTORS	Fri Jun 19 07:53:33 2015 +0200
+++ b/CONTRIBUTORS	Fri Jun 19 07:53:35 2015 +0200
@@ -10,6 +10,10 @@
   Generic partial division in rings as inverse operation
   of multiplication.
 
+* Summer 2015: Manuel Eberl and Florian Haftmann, TUM
+  Type class hierarchy with common algebraic notions of
+  integral (semi)domains like units and associated elements.
+
 
 Contributions to Isabelle2015
 -----------------------------