SUSILAWATI, SISI SUSILAWATI, Akhmad Fauzi, Cecep Kusmana, and Nyoto Santoso. “Strategy and Policy in the Management of Sumatran Orangutan (Pongo Abelii) Conservation Tourism on the Lawang Hill in the Langkat District of North Sumatera”. Jurnal Pengelolaan Sumberdaya Alam dan Lingkungan (Journal of Natural Resources and Environmental Management) 10, no. 1 (March 20, 2020): 1-11. Accessed October 22, 2021. https://jurnal.ipb.ac.id/index.php/jpsl/article/view/28098.