<https://baotiengdan.com/2018/07/28/cs-phai-ket-thuc-do-la-quy-luat-tat-yeu/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://baotiengdan.com/2018/07/28/cs-phai-ket-thuc-do-la-quy-luat-tat-yeu/>