P. Kluegl, M. Atzmueller, and F. Puppe. Proc. LWA 2009, Knowledge Discovery and Machine Learning Track, Darmstadt, Germany, University of Darmstadt, (2009)
K. Wang, T. Walker, and Z. Zheng. KDD '09: Proceedings of the 15th ACM SIGKDD international conference on Knowledge discovery and data mining, page 1355--1364. New York, NY, USA, ACM, (2009)