<https://shinodogg.com/2008/03/08/%e3%82%b9%e3%83%ab%e3%82%ac%e9%8a%80%e8%a1%8c%e3%81%aeibm%e6%8f%90%e8%a8%b4/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://shinodogg.com/2008/03/08/%E3%82%B9%E3%83%AB%E3%82%AC%E9%8A%80%E8%A1%8C%E3%81%AEibm%E6%8F%90%E8%A8%B4/>