<https://ryukokoro.blog/%e3%83%a6%e3%83%bc%e3%83%81%e3%83%a5%e3%83%bc%e3%83%90%e3%83%bc/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://ryukokoro.blog/%E3%83%A6%E3%83%BC%E3%83%81%E3%83%A5%E3%83%BC%E3%83%90%E3%83%BC/>