query: #US presidents and spouses
  #added before 2016-10
  SELECT ?p ?pLabel ?ppicture ?w ?wLabel ?wpicture
  WHERE 
  {
  	wd:Q30 p:P6/ps:P6 ?p .
  	?p wdt:P26 ?w .
     OPTIONAL{
      ?p wdt:P18 ?ppicture .
      ?w wdt:P18 ?wpicture .
      }
  	SERVICE wikibase:label {
  		bd:serviceParam wikibase:language "en" .
  	}
  }