Question: Which non fiction of the Thud is also the field of the Jon Speelman ?
SPARQL query:
PREFIX onto: <http://dbpedia.org/ontology/>
 SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/Thud!> onto:nonFictionSubject ?uri. <http://dbpedia.org/resource/Jon_Speelman> onto:field ?uri}