P. Symeonidis, A. Nanopoulos, and Y. Manolopoulos. RecSys '08: Proceedings of the 2008 ACM conference on Recommender systems, page 43--50. New York, NY, USA, ACM, (2008)
C. Schmitz, A. Hotho, R. Jäschke, and G. Stumme. The Semantic Web: Research and Applications, volume 4011 of LNAI, page 530-544. Heidelberg, Springer, (2006)
I. Dhillon. KDD '01: Proceedings of the seventh ACM SIGKDD international conference on Knowledge discovery and data mining, page 269--274. New York, NY, USA, ACM Press, (2001)