D. Apshvalka, and P. Wendorff. Proceedings of the 6th European Conference on Knowledge Management (ECKM), page 34-41. Academic Conferences Limited, Reading, UK, (September 2005)
S. Dietzold, and S. Auer. Proceedings of International Conference Semantics Systems 2007,
I-SEMANTICS'07, Graz, Austria; September 5 -- 7, 2007, page 290-296. Journal of Univeral Computer Science, (September 2007)