<https://mika-oya.com/%e3%83%97%e3%83%a9%e3%82%a4%e3%83%99%e3%83%bc%e3%83%88/%e3%83%8f%e3%83%bc%e3%83%90%e3%83%aa%e3%82%a6%e3%83%a0/#webpage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://mika-oya.com/%E3%83%97%E3%83%A9%E3%82%A4%E3%83%99%E3%83%BC%E3%83%88/%E3%83%8F%E3%83%BC%E3%83%90%E3%83%AA%E3%82%A6%E3%83%A0/>