@InProceedings{LuWaWo-07,
  author = 	 {Carsten Lutz and Dirk Walther and Frank Wolter},
  booktitle = 	 {Proceedings of the Twentieth International Joint Conference on Artificial Intelligence (IJCAI'07)},
  title = 	 {Conservative Extensions in Expressive Description Logics},
  year = 	 2007,
  pages =        {453-458},
  editor =       {Manuela Veloso},
  publisher =    {AAAI Press}
}