<https://yuyududu45.pixnet.net/blog/post/31313215-2007%e5%b9%b411%e6%9c%8812%e6%97%a5%e9%ae%ae%e5%a5%b6%e9%ab%98%e9%88%a3%e5%90%90%e5%8f%b8>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://yuyududu45.pixnet.net/blog/post/31313215>