Shuang Wang Guoren Wang Xiaoxing Gao Sharing Aggregate Computation of Multiple Group by Queries over Distributed Data Stream. 639-642 2008 CSSE (4) http://dx.doi.org/10.1109/CSSE.2008.476 conf/csse/2008-4 db/conf/csse/csse2008-4.html#WangWG08