Nutritional Differences between Two Orangutan Habitats: Implications for Population Density. oleh Erin R Vogel, Mark E Harrison, Astri Zulfa, Timothy D Bransford, Shauhin E Alavi, Simon Husson, Helen Morrogh-Bernard, Santiano, Twentinolosa Firtsman, Sri Suci Utami-Atmoko, Maria A van Noordwijk, Wartika Rosa Farida