V. Rivera-Pelayo, V. Zacharias, L. Müller, and S. Braun. Proceedings of the 2nd International Conference on Learning Analytics and Knowledge, page 111–114. New York, NY, USA, Association for Computing Machinery, (2012)
A. Gustafsson, and M. B\aang. Proceedings of the 2008 International Conference on Advances in Computer Entertainment Technology, page 232--239. ACM, (2008)
D. Cosley, S. Lawrence, and D. Pennock. VLDB '02: Proceedings of the 28th international conference on Very Large Data Bases, page 35--46. VLDB Endowment, (2002)