<http://midori-fu.com/blog/%e2%99%aa%e4%b8%89%e6%ae%b5%e5%b3%a1%e2%99%aa/#article>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://midori-fu.com/blog/%E2%99%AA%E4%B8%89%E6%AE%B5%E5%B3%A1%E2%99%AA/>