<https://www.mariuri.com/post/2019/07/31/\u306F\u306A\u3061\u3083\u3093>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.mariuri.com/post/2019/07/31/%E3%81%AF%E3%81%AA%E3%81%A1%E3%82%83%E3%82%93>