<https://nona-a.com/blog/2020/03/02/%e7%81%ab%e9%89%a2%e3%81%ae%e6%9a%ae%e3%82%89%e3%81%97/>
<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/>