Graham Morgan Kier Storey Fengyun Lu Expanding Spheres: A Collision Detection Algorithm for Interest Management in Networked Games. 435-440 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3166&spage=435 2004 conf/iwec/2004 ICEC db/conf/iwec/icec2004.html#MorganSL04