<https://nona-a.com/blog/2020/04/26/%e8%87%aa%e7%b2%9b%e6%99%82%e6%9c%9f%e3%82%82%e6%a5%bd%e3%81%97%e3%82%80/>
<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/>