<https://nona-a.com/blog/2018/04/30/%e6%9a%ae%e3%82%89%e3%81%97%e5%a7%8b%e3%82%81%e3%81%a6%e3%81%8a%e3%82%88%e3%81%9d%e5%8d%8a%e5%b9%b4%e3%81%ae%e5%b2%a1%e5%b4%8e%e3%81%ae%e5%ae%b6%e3%81%b8/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://nona-a.com/blog/category/%E6%9A%AE%E3%82%89%E3%81%97/>