Paul Schwartz Lauren Bricker Bruce Campbell Thomas A. Furness Kori Inkpen Lydia Matheson Nobutatsu Nakamura Li-Sheng Shen Susan Tanney Shihming Yen Virtual playground: architectures for a shared virtual world. 43-50 1998 VRST http://doi.acm.org/10.1145/293701.293707 db/conf/vrst/vrst1998.html#SchwartzBCFIMNSTY98