Question: What are the other key people of the non-profit organisations whose one of the  key person is Joe Green ?
SPARQL query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX prop: <http://dbpedia.org/property/>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT ?uri WHERE { ?x prop:keyPeople <http://dbpedia.org/resource/Joe_Green_(entrepreneur)> . ?x prop:keyPeople ?uri . ?x rdf:type onto:Non-ProfitOrganisation}