Xianghua Ding Thomas Erickson Wendy A. Kellogg Stephen Levy Jim Christensen Jeremy B. Sussman Tracee Vetting Wolf William E. Bennett An empirical study of the use of visually enhanced voip audio conferencing: the case of IEAC. 1019-1028 2007 conf/chi/2007 CHI http://doi.acm.org/10.1145/1240624.1240780 db/conf/chi/chi2007.html#DingEKLCSWB07