<https://keeplearning.blog/tag/%e5%85%a5%e5%a2%83%e7%be%8e%e5%9c%8b/#collectionpage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://keeplearning.blog/tag/%E5%85%A5%E5%A2%83%E7%BE%8E%E5%9C%8B/>