W. Xi, E. Fox, W. Fan, B. Zhang, Z. Chen, J. Yan, and D. Zhuang. SIGIR '05: Proceedings of the 28th annual international ACM SIGIR conference on Research and development in information retrieval, page 130--137. New York, NY, USA, ACM, (2005)
E. Kemp, and D. Setungamudalige. CHINZ '06: Proceedings of the 7th ACM SIGCHI New Zealand chapter's international conference on Computer-human interaction, page 61--66. New York, NY, USA, ACM, (2006)