<https://www.den2.org/2009/09/%ef%bc%92%e5%9b%9e%e7%9b%ae%e3%81%af%e7%84%a1%e3%81%84%e3%83%bb%e3%83%bb%e3%83%bb/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.den2.org/2009/09/%EF%BC%92%E5%9B%9E%E7%9B%AE%E3%81%AF%E7%84%A1%E3%81%84%E3%83%BB%E3%83%BB%E3%83%BB/>