R. Kumar, J. Novak, and A. Tomkins. Proceedings of the 12th ACM SIGKDD International Conference on Knowledge Discovery and Data Mining, page 611--617. New York, NY, USA, ACM, (2006)
R. Vatrapu, P. Reimann, S. Bull, and M. Johnson. Proceedings of the Third International Conference on Learning Analytics and Knowledge, page 125--134. New York, NY, USA, ACM, (2013)
R. Guha, R. Kumar, P. Raghavan, and A. Tomkins. Proceedings of the 13th International Conference on World Wide Web, page 403--412. New York, NY, USA, ACM, (2004)