<https://kariyasui.com/%e4%bd%8f%e5%ae%85%e3%83%ad%e3%83%bc%e3%83%b3/post-162/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://kariyasui.com/%E4%BD%8F%E5%AE%85%E3%83%AD%E3%83%BC%E3%83%B3/post-162/>