<https://anq39.com/2020/09/09/%e4%ba%8c%e7%8e%8b%e5%ad%90%e5%b2%b3-2008-4-20/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://anq39.com/2020/09/09/%E4%BA%8C%E7%8E%8B%E5%AD%90%E5%B2%B3-2008-4-20/>