Marek Smid Petr Kremen OnGIS: Semantic Query Broker for Heterogeneous Geospatial Data Sources 32-50 2016 Open Journal of Semantic Web (OJSW) 3 1 https://www.ronpub.com/ojsw/OJSW_2016v3i1n03_Smid.html http://nbn-resolving.de/urn:nbn:de:101:1-201705194936 urn:nbn:de:101:1-201705194936 RonPub UG (haftungsbeschränkt)