<https://hazemoto-k.co.jp/column/2015/09/12/%e3%82%a2%e3%83%aa%e3%82%b9%e5%85%88%e7%94%9f/#blogposting>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://hazemoto-k.co.jp/column/2015/09/12/%E3%82%A2%E3%83%AA%E3%82%B9%E5%85%88%E7%94%9F/>