<https://www.lefthands.net/%e5%88%86%e6%a5%ad%e3%81%a8%e5%8a%b9%e7%8e%87/#article>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.lefthands.net/%E5%88%86%E6%A5%AD%E3%81%A8%E5%8A%B9%E7%8E%87/>