SantosaY., SiregarJ. P., RinaldiD., and RahmanD. A. “Faktor–Faktor Penentu Keberhasilan Pelepasliaran Orangutan Sumatera (Pongo Abelii) Di Taman Nasional Bukit Tigapuluh”. Jurnal Ilmu Pertanian Indonesia, Vol. 17, no. 3, Aug. 2014, pp. 186-91, https://jurnal.ipb.ac.id/index.php/JIPI/article/view/8344.