<https://joint-moving.com/blog/%e3%83%a1%e3%83%b3%e3%83%86%e3%83%8a%e3%83%b3%e3%82%b9%ef%bc%81/#article>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://joint-moving.com/blog/%E3%83%A1%E3%83%B3%E3%83%86%E3%83%8A%E3%83%B3%E3%82%B9%EF%BC%81/>