query: embed.html#SELECT ?item ?itemLabel ?Legacies_of_British_Slave_ownership_person_ID ?Oxford_Dictionary_of_National_Biography_ID WHERE {
    SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
    OPTIONAL { ?item wdt:P3023 ?Legacies_of_British_Slave_ownership_person_ID. }
    OPTIONAL { ?item wdt:P1415 ?Oxford_Dictionary_of_National_Biography_ID. }
   }
  LIMIT 1000