<https://biwakobase.net/2007/08/09/%e8%a7%92%e7%a0%82%e7%b3%96%e3%81%ae%e7%be%8e%e6%84%8f%e8%ad%98/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://biwakobase.net/2007/08/09/%E8%A7%92%E7%A0%82%E7%B3%96%E3%81%AE%E7%BE%8E%E6%84%8F%E8%AD%98/>