<https://itsumohiito.com/5%e5%b9%b4%e7%9b%ae%e3%82%84%e3%82%8a%e3%81%9f%e3%81%84%e3%81%93%e3%81%a8%e3%83%aa%e3%82%b9%e3%83%88%e3%81%ae%e9%80%b2%e6%8d%97/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://itsumohiito.com/5%E5%B9%B4%E7%9B%AE%E3%82%84%E3%82%8A%E3%81%9F%E3%81%84%E3%81%93%E3%81%A8%E3%83%AA%E3%82%B9%E3%83%88%E3%81%AE%E9%80%B2%E6%8D%97/>