I. Horrocks, and U. Sattler. Proceedings of the Seventeenth International Joint Conference on Artificial Intelligence, IJCAI 2001, Seattle, Washington, USA, August 4-10, 2001, page 199-204. Morgan Kaufmann, (2001)
S. Staab, M. Erdmann, A. Mädche, and S. Decker. First Workshop on the Semantic Web at the Fourth
European Conference on Digital Libraries, Lisbon, Portugal, (September 2000)