B. Grau, I. Horrocks, Y. Kazakov, und U. Sattler. IJCAI'07: Proceedings of the 20th international joint conference on Artifical intelligence, Seite 298--303. San Francisco, CA, USA, Morgan Kaufmann Publishers Inc., (2007)
T. Gruber, und G. Olsen. Principles of Knowledge Representation and Reasoning: Proceedings of the 4th International Conference (KR '94): Bonn, Germany: 1994, May, 24 - 27, Seite 258-269. Morgan Kaufmann Publishers, (1994)