<https://cmf8.net/blog/staffblog/1044/attachment/f2bcc913-fab1-4f8d-86e5-5cd37f90d40b/#itempage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://cmf8.net/blog/staffblog/1044/attachment/f2bcc913-fab1-4f8d-86e5-5cd37f90d40b/>