What is {introduction} of {historical period} of {Siege of Leningrad} ?
What is the introduction period of Siege of Leningrad?
SELECT ?answer WHERE { wd:Q151860 wdt:P2348 ?X . ?X wdt:P580 ?answer}
SELECT ?answer WHERE { ?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q151860> . ?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P2348>. ?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?X . ?statement2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?X. ?statement2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P580> . ?statement2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?answer . }
What is the presentation period of Attack of Leningrad?