W. Fury, F. Batliwalla, P. Gregersen, and W. Li. Engineering in Medicine and Biology Society, 2006. EMBS'06. 28th Annual International Conference of the IEEE, page 5531--5534. IEEE, (2006)
J. Yang, and J. Leskovec. Proceedings of the Sixth ACM International Conference on Web Search and Data Mining, page 587--596. New York, NY, USA, ACM, (2013)