which musician wrote the most books?
SELECT DISTINCT ?uri WHERE { ?uri <http://dbpedia.org/ontology/occupation> <http://dbpedia.org/resource/Musician> . ?x <http://dbpedia.org/ontology/author> ?uri . ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Book> . } ORDER BY DESC(COUNT(?x)) OFFSET 0 LIMIT 1
Musician