<https://ajs0414.pixnet.net/blog/post/62397883-%e5%ae%9c%e8%98%ad%e8%bc%95%e6%97%85%e8%a1%8c-%e8%98%ad%e9%99%bd%e5%8d%9a%e7%89%a9%e9%a4%a8>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://ajs0414.pixnet.net/blog/post/62397883>