F. Baader, B. Ganter, B. Sertkaya, und U. Sattler. Proceedings of the 20th international joint conference on Artifical intelligence, Seite 230--235. San Francisco, CA, USA, Morgan Kaufmann Publishers Inc., (2007)
B. Hoser, A. Hotho, R. Jäschke, C. Schmitz, und G. Stumme. The Semantic Web: Research and Applications, Volume 4011 von Lecture Notes in Computer Science, Springer, Berlin/Heidelberg, 10.1007/11762256_38.(2006)