Question: Name the river with mouth palce Essex and source place as Gloucestershire ?
SPARQL query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT ?uri WHERE {?uri onto:mouthPlace <http://dbpedia.org/resource/Essex> . ?uri onto:sourcePlace <http://dbpedia.org/resource/Gloucestershire>  . ?uri rdf:type onto:River}