Junming Huang, Xue-Qi Cheng, Hua-Wei Shen, Tao Zhou, and Xiaolong Jin. 2012. Exploring social influence via posterior effect of word-of-mouth recommendations.  In <em>Proceedings of the fifth ACM international conference on Web search and data mining</em> (WSDM '12). ACM, New York, NY, USA,  573-582. DOI=10.1145/2124295.2124365 http://doi.acm.org/10.1145/2124295.2124365