<https://blog.w-ab.com/2017/05/18/%e4%bb%8a%e6%97%a5%e3%81%ae%e3%81%8a%e5%bc%81%e5%bd%93-579/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://blog.w-ab.com/2017/05/18/%E4%BB%8A%E6%97%A5%E3%81%AE%E3%81%8A%E5%BC%81%E5%BD%93-579/>