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)
R. Mihalcea, and A. Csomai. Proceedings of the sixteenth ACM Conference on information and knowledge management, page 233--242. New York, NY, USA, ACM, (2007)