M. Magableh, A. Cau, H. Zedan, and M. Ward. Proceedings of the IADIS International Conferences Collaborative Technologies 2010 and Web Based Communities 2010, page 178--182. (July 2010)
P. Heymann, A. Paepcke, and H. Garcia-Molina. Third ACM International Conference on Web Search and Data Mining (WSDM2010), page 1--10. Stanford University, (February 2010)