<https://loigiaihay.com/bai-2-mot-so-phuong-phap-bieu-hien-cac-doi-tuong-dia-li-tren-ban-do-e18077.html>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://m.loigiaihay.com/bai-2-mot-so-phuong-phap-bieu-hien-cac-doi-tuong-dia-li-tren-ban-do-e18077.html>