Allison Klein Wilmot Li Michael M. Kazhdan Wagner Toledo Corrêa Adam Finkelstein Thomas A. Funkhouser Non-photorealistic virtual environments. 527-534 2000 SIGGRAPH http://portal.acm.org/citation.cfm?id=344779.345075 db/conf/siggraph/siggraph2000.html#KleinLKCFF00