<https://otherworldsarepossible.org/sakai/%e5%a0%ba%e5%b8%82%e5%8d%97%e5%8c%ba%e3%81%ae%e6%b0%b4%e6%bc%8f%e3%82%8c%e4%bf%ae%e7%90%86/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://otherworldsarepossible.org/sakai/%E5%A0%BA%E5%B8%82%E5%8D%97%E5%8C%BA%E3%81%AE%E6%B0%B4%E6%BC%8F%E3%82%8C%E4%BF%AE%E7%90%86/>