H. van Heerde. Centre for Telematics and Information Technology, University of Twente, Enschede, The Netherlands, (June 2010)CTIT Ph.D. thesis series no. 10-166.
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)