List the served region of the organisations of Trade association.
SELECT DISTINCT ?uri WHERE { ?x <http://dbpedia.org/ontology/type> <http://dbpedia.org/resource/Trade_association> . ?x <http://dbpedia.org/ontology/regionServed> ?uri  . ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Organisation>}
Trade_association