<https://batasyan.com/2015/11/17/%e5%92%8c%e4%bd%90%e6%96%87%e5%8c%96%e3%81%be%e3%81%a4%e3%82%8a/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://batasyan.com/2015/11/17/%E5%92%8C%E4%BD%90%E6%96%87%E5%8C%96%E3%81%BE%E3%81%A4%E3%82%8A/>