Nghi, Tran, Ta Hoa Phuong, Vu Van Phai, Dinh Xuan Thanh, Nguyen Thanh Lan, Nguyen Dinh Thai, & Nguyen Thi Hong. " Adventurous tourism-a potetial realm of world Natural Heritage - National Park Phong Nha - Ke Bang." VNU Journal of Science: Earth and Environmental Sciences [Online], 27.2 (2011): n. pag. Web. 22 Nov. 2024