<https://sawa38blog.com/2020/09/03/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://sawa38blog.com/2020/09/03/%E3%82%A4%E3%83%A1%E3%83%BC%E3%82%B8%E3%81%A7%E3%81%A4%E3%81%8B%E3%82%80%E7%B0%BF%E8%A8%98/>