James E. Pitkow Hinrich Schütze Todd A. Cass Robert Cooley Don Turnbull Andy Edmonds Eytan Adar Thomas M. Breuel 50-55 2002 45 Commun. ACM 9 http://doi.acm.org/10.1145/567498.567526 db/journals/cacm/cacm45.html#PitkowSCCTEAB02