<https://iyirs.com/%e3%83%9f%e3%83%8b%e3%82%aa%e3%83%b3-%e7%9d%80%e3%81%90%e3%82%8b%e3%81%bf/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://iyirs.com/%E3%83%9F%E3%83%8B%E3%82%AA%E3%83%B3-%E7%9D%80%E3%81%90%E3%82%8B%E3%81%BF/>