<https://lafsina.com/lafsinablog/%e7%a7%98%e5%af%86%e3%81%ae%e5%a0%b4%e6%89%80%e3%81%ab%e3%81%97%e3%81%be%e3%81%99%ef%bc%81/#webpage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://lafsina.com/lafsinablog/%E7%A7%98%E5%AF%86%E3%81%AE%E5%A0%B4%E6%89%80%E3%81%AB%E3%81%97%E3%81%BE%E3%81%99%EF%BC%81/>