R. Pon, A. Cardenas, D. Buttler, and T. Critchlow. Proceedings of the 13th ACM SIGKDD international conference on Knowledge discovery and data mining, page 560--569. New York, NY, USA, ACM, (2007)
M. Kompan, and M. Bieliková. E-Commerce and Web Technologies, volume 61 of Lecture Notes in Business Information Processing, Springer Berlin Heidelberg, (2010)