query: PREFIX wd: <http://www.wikidata.org/entity/>
  PREFIX wdt: <http://www.wikidata.org/prop/direct/>
  PREFIX wikibase: <http://wikiba.se/ontology#>
  PREFIX p: <http://www.wikidata.org/prop/>
  PREFIX v: <http://www.wikidata.org/prop/statement/>
  PREFIX q: <http://www.wikidata.org/prop/qualifier/>
  PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
  
  select ?x ?y where {
    ?x wdt:P31 wd:Q21818626 .
    optional { ?x rdfs:label ?y filter (lang(?y) = 'en'). }
    }
  
  