Who wrote the musical based on Mary Poppins?
SELECT DISTINCT ?uri WHERE { ?x <http://dbpedia.org/ontology/basedOn> <http://dbpedia.org/resource/Mary_Poppins> . ?x <http://dbpedia.org/ontology/author> ?uri  . ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Musical>}
Mary_Poppins