<https://www.never-giveup.net/2014/09/%e9%ab%98%e5%86%86%e5%ae%ae%e6%9d%afu-15/#webpage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.never-giveup.net/2014/09/%E9%AB%98%E5%86%86%E5%AE%AE%E6%9D%AFu-15/>