Question: When did Josef Mengele become member of Stahlhelm, Bundder Frontsoldaten?
Paraphrase: Josef Mengele became a member of Stahlhelm, Bundder Frontsoldaten in what year?
SPARQL (Wikidata): SELECT ?value WHERE { wd:Q57109 p:P463 ?s . ?s ps:P463 wd:Q568522 . ?s pq:P580 ?value}