M. Sintek, and S. Decker. ISWC '02: Proceedings of the First International Semantic Web Conference on The Semantic Web, page 364--378. London, UK, Springer-Verlag, (2002)
P. Mitra, G. Wiederhold, and S. Decker. The Emerging Semantic Web, volume 75 of Frontiers in Artificial Intelligence and Applications, IOS press, (2001)