<https://vc-ichinomiya.com/content/8%e6%9c%88%e3%83%95%e3%82%a1%e3%83%83%e3%82%b7%e3%83%a7%e3%83%b3%e3%83%87%e3%83%bc%e5%91%8a%e7%9f%a5%ef%bc%81/#article>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://vc-ichinomiya.com/content/8%E6%9C%88%E3%83%95%E3%82%A1%E3%83%83%E3%82%B7%E3%83%A7%E3%83%B3%E3%83%87%E3%83%BC%E5%91%8A%E7%9F%A5%EF%BC%81/>