<https://matsujirushi-blog.com/%e3%82%88%e3%81%8f%e3%81%82%e3%82%8b%e8%b3%aa%e5%95%8f/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://matsujirushi-blog.com/%E3%82%88%E3%81%8F%E3%81%82%E3%82%8B%E8%B3%AA%E5%95%8F/>