H. Li, Y. Cao, J. Xu, Y. Hu, S. Li, and D. Meyerzon. CIKM '05: Proceedings of the 14th ACM international conference on Information and knowledge management, page 460--468. New York, NY, USA, ACM, (2005)
J. Zhang, and M. Ackerman. GROUP '05: Proceedings of the 2005 international ACM SIGGROUP conference on Supporting group work, page 71--80. New York, NY, USA, ACM Press, (2005)