Thanh, T., & 		Hải, N.
(2002).
 Lượng hóa giá trị du lịch vịnh Hạ Long.
<em>VNU Journal Of Science: Natural Sciences And Technology, 18</em>(4).
Retrieved from <a href="https://js.vnu.edu.vn/NST/article/view/3154" target="_new">https://js.vnu.edu.vn/NST/article/view/3154</a>