<https://quality-reform.com/%e3%82%b9%e3%82%bf%e3%83%83%e3%83%95%e7%b4%b9%e4%bb%8b/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://quality-reform.com/qr%E3%82%B9%E3%82%BF%E3%83%83%E3%83%95%E3%83%96%E3%83%AD%E3%82%B0/page/7/>