Matthew Perry Amit P. Sheth Farshad Hakimpour Prateek Jain Supporting Complex Thematic, Spatial and Temporal Queries over Semantic Web Data. 228-246 2007 conf/geos/2007 GeoS http://dx.doi.org/10.1007/978-3-540-76876-0_15 db/conf/geos/geos2007.html#PerrySHJ07