<https://dictionary.goo.ne.jp/word/%E5%AF%92%E6%B0%97_%28%E3%81%95%E3%82%80%E3%81%91%29/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://dictionary.goo.ne.jp/word/%E5%AF%92%E6%B0%97_%28%E3%81%95%E3%82%80%E3%81%91%29/>