D. Fisher, A. Brush, E. Gleave, and M. Smith. CSCW '06: Proceedings of the 2006 20th anniversary conference on Computer supported cooperative work, page 309--312. New York, NY, USA, ACM, (2006)
S. Whittaker, and C. Sidner. CHI '96: Proceedings of the SIGCHI conference on Human factors in computing systems, page 276--283. New York, NY, USA, ACM, (1996)