<https://harikyuanshishi.com/%e3%82%aa%e3%83%bc%e3%83%80%e3%83%bc%e3%82%b1%e3%82%a2%e3%82%b3%e3%83%bc%e3%82%b9/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://harikyuanshishi.com/%E3%82%AA%E3%83%BC%E3%83%80%E3%83%BC%E3%82%B1%E3%82%A2%E3%82%B3%E3%83%BC%E3%82%B9/>