Sang Chul Ahn Ig-Jae Kim Hyoung-Gon Kim Yong-Moo Kwon Heedong Ko Audience interaction for virtual reality theater and its implementation. 41-45 2001 VRST http://doi.acm.org/10.1145/505008.505016 db/conf/vrst/vrst2001.html#AhnKKKK01