<https://www.yaizu-blog.com/tag/%e6%b8%85%e8%a6%8b%e7%94%b0%e5%85%ac%e5%9c%92/#webpage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.yaizu-blog.com/tag/%E6%B8%85%E8%A6%8B%E7%94%B0%E5%85%AC%E5%9C%92/>