<https://re-generate.jp/articles/tag/%e6%b0%97%e5%80%99%e5%a4%89%e5%8b%95/#primaryimage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://re-generate.jp/articles/tag/%E6%B0%97%E5%80%99%E5%A4%89%E5%8B%95/>