Question: Which key person of maryland jockey club is the appointer of Joseph Clay ?
SPARQL:
 SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/Joseph_Clay_(Georgia)> <http://dbpedia.org/ontology/appointer> ?uri. <http://dbpedia.org/resource/Maryland_Jockey_Club> <http://dbpedia.org/property/keyPeople> ?uri}