Q. He, D. Kifer, J. Pei, P. Mitra, and C. Giles. Proceedings of the fourth ACM international conference on Web search and data mining, page 755--764. New York, NY, USA, ACM, (2011)
D. Schall, and F. Skopik. Proceedings of the 15th international conference on Advances in databases and information systems, page 285--301. Berlin, Heidelberg, Springer-Verlag, (2011)
Y. Sure, S. Bloehdorn, P. Haase, J. Hartmann, and D. Oberle. Proceedings of the 12th Portuguese Conference on Artificial Intelligence - Progress in Artificial Intelligence (EPIA 2005), volume 3803 of LNCS, page 218 - 231. Covilha, Portugal, Springer, (Dezember 2005)