Mahady Hasan Muhammad Aamir Cheema Xuemin Lin Ying Zhang Efficient Construction of Safe Regions for Moving kNN Queries over Dynamic Datasets. 373-379 2009 SSTD http://dx.doi.org/10.1007/978-3-642-02982-0_24 conf/ssd/2009 db/conf/ssd/sstd2009.html#HasanCLZ09