<https://nona-a.com/blog/2021/07/04/%e6%97%a5%e6%9c%ac%e3%81%ae%e6%b0%91%e5%ae%b6%e3%81%ab%e4%bd%8f%e3%82%80%e7%90%86%e7%94%b1%e2%91%a0/>
<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/>