<https://ozakifarm.net/blog/%e7%ab%b9%e7%82%ad%e3%81%ae%e4%bf%ae%e8%a1%8c#webpage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://ozakifarm.net/blog/%E7%AB%B9%E7%82%AD%E3%81%AE%E4%BF%AE%E8%A1%8C>