Xiangyuan Dai Man Lung Yiu Nikos Mamoulis Yufei Tao Michail Vaitis Probabilistic Spatial Queries on Existentially Uncertain Data. 400-417 2005 conf/ssd/2005 SSTD http://dx.doi.org/10.1007/11535331_23 db/conf/ssd/sstd2005.html#DaiYMTV05