<https://luckylong.pixnet.net/blog/post/53409262-%e5%a4%a2%e6%83%b3%e8%a1%9757%e8%99%9f%ef%bc%9a%e5%be%9e%e5%a4%a7%e8%82%a1%e6%9d%b1%e6%8c%81%e8%82%a1%e8%ae%8a%e5%8c%96%ef%bc%8c%e7%aa%ba%e8%a6%8b%e8%82%a1%e5%83%b9%e8%a6%81>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://luckylong.pixnet.net/blog/post/53409262>