<https://katrina720926.pixnet.net/blog/post/69554452-%ef%bc%8a20190101%ef%bc%8a%e9%9f%93%e5%9c%8b%e9%a6%96%e7%88%be%e4%b8%89%e8%a8%aaday5%ef%bc%8a%e6%96%b0%e6%b2%99%e6%b4%9e%e6%9e%97%e8%94%ad%e9%81%93%ef%bc%8a>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://katrina720926.pixnet.net/blog/post/69554452>