<https://oekaki.be/2021/05/10/%e5%8d%b0%e9%91%91%e3%81%a4%e3%81%8f%e3%82%8a/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://oekaki.be/2021/05/10/%E5%8D%B0%E9%91%91%E3%81%A4%E3%81%8F%E3%82%8A/>