query: SELECT ?item ?itemLabel ?Den ?Dde ?Dnl WHERE {
    SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en,de". }
    ?item schema:description "painting by Unbekannt"@en.
    ?item wdt:P31 wd:Q3305213.
    OPTIONAL { ?item schema:description ?Den. FILTER((LANG(?Den)) = "en") }
    OPTIONAL { ?item schema:description ?Dde. FILTER((LANG(?Dde)) = "de") }
    OPTIONAL { ?item schema:description ?Dnl. FILTER((LANG(?Dnl)) = "nl") }
  }