S. Lee, and A. Chun. ACOS'07: Proceedings of the 6th Conference on WSEAS International Conference on Applied Computer Science, page 88--93. Stevens Point, Wisconsin, USA, World Scientific and Engineering Academy and Society (WSEAS), (2007)
M. Ames, and M. Naaman. CHI '07: Proceedings of the SIGCHI conference on Human factors in computing systems, page 971--980. New York, NY, USA, ACM Press, (2007)