<https://naganishi.org/faqs/%e2%96%a0%e6%94%be%e8%aa%b2%e3%81%a3%e3%81%a6%ef%bc%9f>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://naganishi.org/faqs/%E2%96%A0%E6%94%BE%E8%AA%B2%E3%81%A3%E3%81%A6%EF%BC%9F>