Question: Rivers from which countries flow into the Caspian?
SPARQL query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT ?uri WHERE { ?x onto:riverMouth <http://dbpedia.org/resource/Caspian_Sea> . ?x onto:sourceCountry ?uri  . ?x rdf:type onto:River}