Niningsih, L., H. S. Alikodra, S. S. U. Atmoko, and Y. A. Mulyani. “Habitat Characteristic of Pongo Pygmaeus Morio in Prevab Area, Kutai National Park, Borneo, Indonesia”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 30, no. 3, Nov. 2016, pp. 8-20, https://www.gssrr.org/index.php/JournalOfBasicAndApplied/article/view/6517.