NGHI, Tran et al. Adventurous tourism-a potetial realm of world Natural Heritage - National Park Phong Nha - Ke Bang. VNU Journal of Science: Earth and Environmental Sciences, [S.l.], v. 27, n. 2, june 2011. ISSN 2588-1094. Available at: <https://js.vnu.edu.vn/EES/article/view/1503>. Date accessed: 23 dec. 2024.