A. Brew, D. Greene, und P. Cunningham. Proceedings of the 19th European Conference on Artificial Intelligence, Volume 215 von Frontiers in Artificial Intelligence and Applications, Seite 145--150. Amsterdam, The Netherlands, The Netherlands, IOS Press, (2010)
T. Rattenbury, N. Good, und M. Naaman. SIGIR '07: Proceedings of the 30th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, Seite 103--110. New York, NY, USA, ACM Press, (2007)