<https://leafyeh.com/category/%e5%8f%b0%e5%8c%97%e5%b8%82-%e7%be%8e%e9%a3%9f-%e9%a4%90%e5%bb%b3-%e5%b0%8f%e5%90%83/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://leafyeh.com/post-114596285/>