<https://staffblog.ns-co.jp/2020/09/03/%e8%87%aa%e5%b7%b1%e5%88%86%e6%9e%90%e3%80%82/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://staffblog.ns-co.jp/2020/09/03/%E8%87%AA%E5%B7%B1%E5%88%86%E6%9E%90%E3%80%82/>