B. Grosof, I. Horrocks, R. Volz, and S. Decker. WWW '03: Proceedings of the 12th International World Wide Web Conference, Budapest, Hungary, page 48-57. (2003)
R. Studer, D. Fensel, S. Decker, and V. Benjamins. volume XPS 99: Knowledge-Based Systems of Lecture Notes in Artificial Intelligence, page 1--23. Springer-Verlag, Berlin, (1999)