A. Goyal, F. Bonchi, and L. Lakshmanan. WSDM '10: Proceedings of the third ACM international conference on Web search and data mining, page 241--250. New York, NY, USA, ACM, (2010)
H. Kwak, C. Lee, H. Park, and S. Moon. WWW '10: Proceedings of the 19th international conference on World wide web, page 591--600. New York, NY, USA, ACM, (2010)