Van Hieu, Nguyen, 		Nam, Nguyen Hoang, 		Van Trung, Pham, AND 		Minh Tuan, Tran.
" Estimation of Tourists’ Willingness to Pay  in Ba Vi National Park: Choice Experiment Method" <em>VNU Journal of Science: Policy and Management Studies</em> [Online], Volume 35 Number 4 (24 December 2019)