Question: Which rivers start in a country whose leader is Irene Mambilima?
SPARQL query: SELECT DISTINCT ?uri WHERE { ?x <http://dbpedia.org/property/leaderName> <http://dbpedia.org/resource/Irene_Mambilima> . ?uri <http://dbpedia.org/ontology/sourceCountry> ?x  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/River>}
Answer: The rivers whose source country's leader name is Irene Mambilima are [Luvua River, Kafue River, Sakeji River, Zambezi].