<https://keikengakusyu.or.jp/%e3%82%b9%e3%83%88%e3%83%ac%e3%82%b9%e3%81%a8%e3%81%ae%e4%bb%98%e3%81%8d%e5%90%88%e3%81%84%e6%96%b9%e2%91%aa/#webpage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://keikengakusyu.or.jp/%E3%82%B9%E3%83%88%E3%83%AC%E3%82%B9%E3%81%A8%E3%81%AE%E4%BB%98%E3%81%8D%E5%90%88%E3%81%84%E6%96%B9%E2%91%AA/>