Ann Q. Gates G. Randy Keller Leonardo Salayandia Paulo Pinheiro da Silva Flor Salcedo The Gravity Data Ontology: Laying the Foundation for Workflow-Driven Ontologies. 278-287 2007 conf/geos/2007 GeoS http://dx.doi.org/10.1007/978-3-540-76876-0_19 db/conf/geos/geos2007.html#GatesKSSS07