query: SELECT DISTINCT ?item ?en ?pl WHERE {
    ?item (wdt:P31/wdt:P279*) wd:Q15334.
    ?item rdfs:label ?pl.
    OPTIONAL {
      ?item rdfs:label ?en.
      FILTER((LANG(?en)) = "en")
    }
    FILTER((LANG(?pl)) = "pl")
  }