Julita Vassileva Lingling Sun Evolving a Social Visualization Design Aimed at Increasing Participation in a Class-Based Online Community. 443-466 2008 17 Int. J. Cooperative Inf. Syst. 4 http://dx.doi.org/10.1142/S0218843008001932 db/journals/ijcis/ijcis17.html#VassilevaS08