Simanjorang, Lely Pratiwi, Irwan Sukri Banuwa, Rahmat Safe’i, and Agus Setiawan. “Economic Valuation of Sipiso-Piso Waterfall With Travel Cost Method and Willingness to Pay”. Jurnal Silva Tropika 2, no. 2 (December 30, 2018): 52–58. Accessed April 5, 2025. https://online-journal.unja.ac.id/STP/article/view/5423.