<https://rulichsu.pixnet.net/blog/post/415952356-%e9%86%ac%e7%88%86%e8%b1%ac%e8%82%9d>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://rulichsu.pixnet.net/blog/post/415952356-%E9%86%AC%E7%88%86%E8%B1%AC%E8%82%9D>