Shuai Yuan Jun Shen Jun Yan A Practical Geographic Ontology for Spatial Web Services. 579-580 2008 IEEE SCC (2) http://doi.ieeecomputersociety.org/10.1109/SCC.2008.15 conf/IEEEscc/2008 db/conf/IEEEscc/scc2008.html#YuanSY08