Tell me the start and end time of John Steinbeck and wife Carol Henning.
SELECT ?value1 ?value2 WHERE { wd:Q39212 p:P26 ?s . ?s ps:P26 wd:Q22273837 . ?s pq:P580 ?value1 . ?s pq:P582 ?value2 }
john steinbeck: Q39212 : Q22273837