1. C. Beierle, U. Hedstück, U. Pietat, P. H. Schmitt, and J. Siekmann. An order-sorted logic for knowledge representation systems. Technical Report 113, IWBS, April 1990.
2. Michel Chein and Marie-Laure Mugnier. Conceptual graphs: fundamental notions. Révue d'Intelligence Artificielle, 6(4):365–406, 1992.
3. Gerard Ellis, Robert Levinson, William Rich, and John F. Sowa, editors. Conceptual Structures: Applications, Implementation and Theory — Proceedings of the Third International Conference on Conceptual Structures, volume 954 of Lecture Notes in Artificial Intelligence, Santa Cruz, USA, August 1995. Springer-Verlag.
4. John Esch and Robert Levinson. An implementation model for contexts and negation in conceptual graphs. In Ellis et al. [3], pages 247–262.
5. Pavel Kocura. Conceptual graph canonicity and semantic constraints. In Peter W. Eklund, Gerard Ellis, and Graham Mann, editors, Conceptual Structures: Knowledge Representation as Interlingua — Auxiliary Proceedings of the Fourth International Conference on Conceptual Structures, pages 133–145, Sydney, Australia, August 1996. University of New South Wales.