S. Jeffery, M. Franklin, and A. Halevy. Proceedings of the 2008 ACM SIGMOD international conference on Management of data, page 847--860. New York, NY, USA, ACM, (2008)
M. Ageev, Q. Guo, D. Lagun, and E. Agichtein. Proceedings of the 34th international ACM SIGIR conference on Research and development in Information Retrieval, page 345--354. New York, NY, USA, ACM, (2011)