Rivers which end in Arkansas go through which cities?
SELECT DISTINCT ?uri WHERE { ?x <http://dbpedia.org/ontology/mouthMountain> <http://dbpedia.org/resource/Arkansas> . ?x <http://dbpedia.org/ontology/city> ?uri  . ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/River>}
Arkansas