Question: Which river has St. Louis as mouth mountain and Madison River as a right tributary?
SPARQL query: SELECT DISTINCT ?uri WHERE {?uri <http://dbpedia.org/ontology/mouthMountain> <http://dbpedia.org/resource/St._Louis> . ?uri <http://dbpedia.org/ontology/rightTributary> <http://dbpedia.org/resource/Madison_River>  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/River>}
Answer: The river whose mouth mountain is St. Louis and the right tributary is Madison River is [Missouri River].