Kevin Shaw Elias Ioup John Sample Mahdi Abdelguerfi Olivier Tabone Efficient Approximation of Spatial Network Queries using the M-Tree with Road Network Embedding. 11 2007 conf/ssdbm/2007 SSDBM http://doi.ieeecomputersociety.org/10.1109/SSDBM.2007.11 db/conf/ssdbm/ssdbm2007.html#ShawISAT07