<https://irodori-net.com/blog/2020/01/%e3%80%8c%e7%a6%8f%e8%a2%8b%e3%80%8d%e5%ae%8c%e5%a3%b2%e5%be%a1%e7%a4%bc%ef%bc%81/#listItem>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://irodori-net.com/blog/2020/01/%E3%80%8C%E7%A6%8F%E8%A2%8B%E3%80%8D%E5%AE%8C%E5%A3%B2%E5%BE%A1%E7%A4%BC%EF%BC%81/>