<https://www.higashishiten.com/blog/category/%e6%9f%bf%e3%81%ae%e7%95%91%e3%81%ab%e3%81%a6/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.higashishiten.com/blog/category/%E6%9F%BF%E3%81%AE%E7%95%91%E3%81%AB%E3%81%A6/>