diff --git a/doc/gf-bib.bib b/doc/gf-bib.bib
index 5a9cd3828..c6f1d0b94 100644
--- a/doc/gf-bib.bib
+++ b/doc/gf-bib.bib
@@ -103,6 +103,15 @@
   year = 2005
 }
 
+@book{keybook,
+        AUTHOR  = {B. Beckert and R. Hähnle and P. Schmitt},
+        TITLE   = {{Verification of Object-Oriented Software: The KeY Approach}},
+        YEAR    = {2006},
+        series  = lncs,
+        volume  = {4334}, 
+        PUBLISHER = {{Springer-Verlag}}
+}
+
 @book{stroustrup,
         AUTHOR  = {B. Stroustrup},
         TITLE   = {{The C++ Programming Language, Third Edition}},