1. ISO/TC 211 Geographic Information/Geomatics. http://www.isotc211.org/.
2. Open Geospatial Consortium (OGC). http://www.ogc.org.
3. World Wide Web Consortium (W3C). http://www.w3.org/.
4. European Commission (EC). INSPIRE Directive 2007/2/EC. http://eur-lex.europa.eu/JOHtml.do?uri=OJ:L:2007:108:SOM:EN:HTML.
5. OGC. GeoSPARQL Standard—A Geographic Query Language for RDF Data. https://portal.opengeospatial.org/files/?artifact_id=47664.