<https://e-visavis.com/pgcakes/%e7%94%b1%e5%b8%83%e9%99%a2%e3%81%ae%e6%a3%ae%e3%81%ae%e3%83%81%e3%83%bc%e3%82%ba%e3%82%b1%e3%83%bc%e3%82%ad/#listItem>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://e-visavis.com/pgcakes/%E7%94%B1%E5%B8%83%E9%99%A2%E3%81%AE%E6%A3%AE%E3%81%AE%E3%83%81%E3%83%BC%E3%82%BA%E3%82%B1%E3%83%BC%E3%82%AD/>