<https://sapporo-sokuho.com/archives/tag/%e3%83%94%e3%82%b6%e9%85%8d%e9%81%94>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://sapporo-sokuho.com/archives/tag/%E3%83%94%E3%82%B6%E9%85%8D%E9%81%94>