<https://www.garphie.com/blog/post/32755940-%e6%84%9b%e4%bd%a0%e6%89%8d%e8%ae%93%e4%bd%a0%e5%90%83%e7%ac%ac%e4%b8%80%e5%8f%a3>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.garphie.com/blog/post/32755940-%E6%84%9B%E4%BD%A0%E6%89%8D%E8%AE%93%E4%BD%A0%E5%90%83%E7%AC%AC%E4%B8%80%E5%8F%A3>