<https://fumicyanblog.com/%e8%bb%a2%e3%81%b0%e3%81%ac%e5%85%88%e3%81%ae%e6%95%a3%e6%ad%a9/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://fumicyanblog.com/%E8%BB%A2%E3%81%B0%E3%81%AC%E5%85%88%E3%81%AE%E6%95%A3%E6%AD%A9/>