@inproceedings{MuellerPoetzsch-Heffter97c,
  AUTHOR =	 { M{\"u}ller, P. and Poetzsch-Heffter, A. },
  TITLE =	 { Preserving the Correctness of Object-Oriented
                  Programs under Extension},
  YEAR =	 {1997},
  EDITOR =	 {Berghammer, R. and Simon, F.},
  pages =        {43--52},
  BOOKTITLE =	 {Programming Languages and Fundamentals of
                  Programming},
  ORGANIZATION = {Christian-Albrechts-Universit\"at Kiel},
  NOTE =	 {Technical Report 9717}
}