<https://taiwan-plus.com/archives/1757/%e5%8f%b0%e5%8c%97%e5%9c%b0%e4%b8%8b%e9%89%84>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://taiwan-plus.com/archives/1757/%E5%8F%B0%E5%8C%97%E5%9C%B0%E4%B8%8B%E9%89%84>