what is the {start time} for {Josef Mengele} has {member of} as {Stahlhelm, Bund der Frontsoldaten} ?
Josef Mengele became a member of Stahlhelm, Bundder Frontsoldaten in what year?
When did Josef Mengele become member of Stahlhelm, Bundder Frontsoldaten?
SELECT ?y WHERE { ?i property:start_time ?y . resource:Josef_Mengele property:member_of ?i . ?i property:member_of resource:Der_Stahlhelm,_Bund_der_Frontsoldaten }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q57109> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P463> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q568522> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q57109 p:P463 ?s . ?s ps:P463 wd:Q568522 . ?s pq:P580 ?value}