Thanh, Pham, Ngoc, Dang, Van Truong, Tran, Cao Huan, Nguyen, AND Vu Viet Quan, Du. " Evaluate the Economic Value of the Recreational Services of the Hon Yen Complex in Phu Yen Province" VNU Journal of Science: Earth and Environmental Sciences [Online], Volume 41 Number 1 (28 February 2025)