What is the river whose mouth locations are Arctic Ocean and Laptev Sea?
SELECT DISTINCT ?uri WHERE { ?uri <http://dbpedia.org/property/mouthLocation> <http://dbpedia.org/resource/Arctic_Ocean> . ?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>}
Arctic_Ocean Laptev_Sea