<https://rubikon-seminare.com/tag/%e8%93%ae%e5%ae%9f%e3%82%af%e3%83%ac%e3%82%a2/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://rubikon-seminare.com/tag/%E8%93%AE%E5%AE%9F%E3%82%AF%E3%83%AC%E3%82%A2/page/2/>