C. Jian nan, Z. Peng yi, Z. Si yi, Z. Chuang, and H. Ying. WRI Global Congress on Intelligent Systems (GCIS '09), Xiamen, China, 2, page 133--138. Los Alamitos, CA, IEEE Computer Society, (2009)
B. Evans, and E. Chi. CSCW '08: Proceedings of the ACM 2008 conference on Computer supported cooperative work, page 485--494. New York, NY, USA, ACM, (2008)