Miguel Rodríguez Luaces José R. Paramá Oscar Pedreira Diego Seco An Ontology-Based Index to Retrieve Documents with Geographic Information. 384-400 2008 SSDBM http://dx.doi.org/10.1007/978-3-540-69497-7_25 conf/ssdbm/2008 db/conf/ssdbm/ssdbm2008.html#LuacesPPS08