<https://serenityteen.pixnet.net/blog/post/32565355-%e3%80%8a%e5%85%89%e7%9a%84%e8%aa%b2%e7%a8%8b%e3%80%8b%e5%88%9d%e9%9a%8e%e7%ac%ac%e4%b8%80%e7%b4%9a%e6%ac%a1%ef%bc%8c2016-01-29%e9%80%b1%e4%ba%94%e6%99%9a>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://serenityteen.pixnet.net/blog/post/32565355>