ASTUTIP., YUSUFT. L., HAYESE., MAHESHWARIH., SJAHFIRDIL., and SAJUTHID., “Diurnal Patterns of Testosterone and Cortisol Metabolites in Fecal of Javan Gibbons (Hylobates moloch) in Captivity”, HAYATI J Biosci, vol. 13, no. 2, p. 69, 1.