<https://ebeshi.com/silk/%e5%8d%83%e6%9c%ac%e6%a1%9c%e7%99%bb%e5%b1%b1-4/#article>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://ebeshi.com/silk/%E5%8D%83%E6%9C%AC%E6%A1%9C%E7%99%BB%E5%B1%B1-4/>