Question: Which river's source mountain is Baikal Mountains and is located in Laptev Sea ?
SPARQL:
SELECT DISTINCT ?uri WHERE {?uri <http://dbpedia.org/ontology/sourceMountain> <http://dbpedia.org/resource/Baikal_Mountains> . ?uri <http://dbpedia.org/property/mouthLocation> <http://dbpedia.org/resource/Laptev_Sea>  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/River>}