Question: Who is the producer of the song which is the previous work of He's a Liar ?
SPARQL:
SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/He's_a_Liar> <http://dbpedia.org/ontology/previousWork> ?x . ?x <http://dbpedia.org/ontology/producer> ?uri . ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Song>}