M. Granitzer, M. Hristakeva, R. Knight, K. Jack, and R. Kern. Proceedings of the 2nd International Conference on Web Intelligence, Mining and Semantics, page 19:1--19:8. New York, NY, USA, ACM, (2012)
T. Rattenbury, N. Good, and M. Naaman. SIGIR '07: Proceedings of the 30th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, page 103--110. New York, NY, USA, ACM Press, (2007)