<https://yurinokunikara.com/2017/12/15/%e5%ae%9d%e7%9f%b3%e3%81%ae%e5%9b%bd%e3%80%80%ef%bc%91%ef%bc%90%e8%a9%b1%e6%84%9f%e6%83%b3/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://yurinokunikara.com/2017/12/15/%E5%AE%9D%E7%9F%B3%E3%81%AE%E5%9B%BD%E3%80%80%EF%BC%91%EF%BC%90%E8%A9%B1%E6%84%9F%E6%83%B3/>