<https://www.slidefactory.vn/5-tu-khoa-quy-gia-tao-suc-nang-cho-bai-thuyet-trinh-cua-ban/#webpage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.slidefactory.vn/5-tu-khoa-quy-gia-tao-suc-nang-cho-bai-thuyet-trinh-cua-ban/>