<https://olive-bird.com/%e6%b8%85%e9%87%8c%e5%ba%97%e3%81%ae%e5%a0%b4%e6%89%80%e3%81%ab%e3%81%a4%e3%81%84%e3%81%a6/#blogposting>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://olive-bird.com/%E6%B8%85%E9%87%8C%E5%BA%97%E3%81%AE%E5%A0%B4%E6%89%80%E3%81%AB%E3%81%A4%E3%81%84%E3%81%A6/>