query: SELECT DISTINCT ?item ?itemLabel
  WHERE {
    ?item wikibase:statements 0; wikibase:sitelinks 1 .
   
     FILTER EXISTS {
      ?article schema:about ?item .
      ?article schema:isPartOf <https://pl.wikipedia.org/>
    }
    SERVICE wikibase:label { bd:serviceParam wikibase:language "pl" }
  }
  ORDER BY ?item
  limit 50