Ligang Dong Bharadwaj Veeravalli GEMA: An Object Replacement Algorithm for Cooperative Web Proxy Systems. 103-130 2004 23 Multimedia Tools Appl. 2 http://springerlink.metapress.com/index/10.1023/B:MTAP.0000026843.40259.28 db/journals/mta/mta23.html#DongV04