<https://alain-style.com/blog/%e5%a4%a9%e4%b8%8b%e4%ba%ba%e3%81%ae%e5%b8%ab/#primaryimage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://alain-style.com/blog/%E5%A4%A9%E4%B8%8B%E4%BA%BA%E3%81%AE%E5%B8%AB/>