<https://blog.eotona.com/%e3%81%8b%e3%81%91%e3%81%8c%e3%81%88%e3%81%ae%e3%81%aa%e3%81%84%e5%9b%bd/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://blog.eotona.com/%E3%81%8B%E3%81%91%E3%81%8C%E3%81%88%E3%81%AE%E3%81%AA%E3%81%84%E5%9B%BD/>