C. Trattner, D. Helic, P. Singer, and M. Strohmaier. Proceedings of the 12th International Conference on Knowledge Management and Knowledge Technologies, page 14. ACM, (2012)
M. Möller, S. Regel, and M. Sintek. The Semantic Web: Research and Applications, 6th European Semantic Web Conference, ESWC 2009, Heraklion, Crete, Greece, volume 5554 of Lecture Notes in Computer Science, Springer, Berlin, (2009)