What is the {airport} for {airline hub} of {Delta Air Lines}
Delta Airlines has it's hub located in what major airport?
Which airport is the hub of Delta Air Lines?
SELECT DISTINCT ?n WHERE { ?n rdf:type ontology:airport . resource:Delta_Air_Lines property:airline_hub ?n }
select distinct ?obj where { ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q188920> . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P113> . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj . ?obj <http://www.wikidata.org/entity/P31> <http://wikidata.dbpedia.org/resource/Q1248784> } 
 select distinct ?obj where { wd:Q188920 wdt:P113 ?obj . ?obj wdt:P31 wd:Q1248784 } 
Hartsfield–Jackson Atlanta International Airport LaGuardia Airport Salt Lake City International Airport Detroit Metropolitan Wayne County Airport Logan International Airport Memphis International Airport Los Angeles International Airport Amsterdam Airport Schiphol Seattle–Tacoma International Airport Narita International Airport