In: J. G. Neal; S. M. Walter (Hrsg.). Natural Language Processing Systems Workshop: Final Technical Report. Pages 79-96, RL-TR, Vol. 91-362, Rome Laboratory, New York, 1991.
In: John Mylopoulos; Raymond Reiter (Hrsg.). Proceedings of the 12th International Joint Conference on Artificial Intelligence. International Joint Conference on Artificial Intelligence (IJCAI-91), August 24-30, Sydney, NSW, Australia, Pages 1003-1011, Morgan Kaufmann Publishers, 1991.
In: Proceedings of the 5th Conference of the European Chapter of the ACL. Conference of the European Chapter of the Association for Computational Linguistics (EACL-91), 5th, April 9-11, Berlin, Germany, Pages 113-118, ACL, 1991.
In: Harold Boley; M.M. Richter (Hrsg.). International Workshop on Processing Declarative Knowledge. International Workshop on Processing Declarative Knowledge (PDK-91), July 1-3, Kaiserslautern, Germany, Pages 161-170, Lecture Notes in Computer Science (LNCS), Springer, 1991.