query: # items with no father or no mother
  SELECT DISTINCT ?item ?itemLabel WHERE {
    { ?item a wdno:P22. }
    UNION
    { ?item a wdno:P25. }
    MINUS { ?item wikibase:rank []. } # filter out statement nodes
    SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
  }