<https://dxr.jp/archives/tag/%e5%a4%a7%e6%97%a5%e6%9c%ac%e5%8d%b0%e5%88%b7#webpage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://dxr.jp/archives/tag/%E5%A4%A7%E6%97%A5%E6%9C%AC%E5%8D%B0%E5%88%B7>