query: SELECT ?entity ?entityLabel ?entityDescription 
  WHERE
  {
    ?entity wdt:P31* wd:Q20427548 . 
    MINUS { ?entity wdt:P131 []; wdt:P31* wd:Q20427548  } 
    SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en" }
  }
  LIMIT 1000