Question: What is the total number of other non-fiction subject of the books whose one of the subject is Racism?
SPARQL:
 SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/ontology/nonFictionSubject> <http://dbpedia.org/resource/Racism> . ?x <http://dbpedia.org/ontology/nonFictionSubject> ?uri }