How many books have been penned by Miguel de Cervantes?
SELECT DISTINCT COUNT(?uri) WHERE {?uri <http://dbpedia.org/ontology/author> <http://dbpedia.org/resource/Miguel_de_Cervantes>  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Book>}
Miguel_de_Cervantes