Xuegang Huang Christian S. Jensen Hua Lu Simonas Saltenis S-GRID: A Versatile Approach to Efficient Query Processing in Spatial Networks. 93-111 2007 conf/ssd/2007 SSTD http://dx.doi.org/10.1007/978-3-540-73540-3_6 db/conf/ssd/sstd2007.html#HuangJLS07