<https://sinya690627.pixnet.net/blog/post/158861330-%e3%80%8a%e9%81%8a%e6%88%b2%e5%a4%a9%e5%a0%82%e3%80%8b%e4%ba%9e%e6%b4%b2%e5%a8%9b%e6%a8%82%e5%9f%8e-%e5%9c%a8%e5%ae%b6%e4%b8%8a%e7%b6%b2%e4%b9%9f%e8%83%bd%e7%8e%a9%e5%8d%9a>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://sinya690627.pixnet.net/blog/post/158861330>