<http://banlo.com/blog/2004/10/05/%e4%b8%96%e7%95%8c%e3%81%a7%e5%be%a9%e6%b4%bb%e3%80%8c%e3%81%9f%e3%81%be%e3%81%94%e3%81%a3%e3%81%a1%e3%80%8d/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://banlo.com/blog/2004/10/05/%E4%B8%96%E7%95%8C%E3%81%A7%E5%BE%A9%E6%B4%BB%E3%80%8C%E3%81%9F%E3%81%BE%E3%81%94%E3%81%A3%E3%81%A1%E3%80%8D/>