Pair bonds and monogamy in wild siamang (Hylobates syndactylus) and white-handed gibbon (Hylobates lar) in Northern Sumatra - Palombit, Ryne Arthur (Ann Arbor, Mich. : University Microfilms International, 1993)
Thesis (Ph.D.)-University of California, 1992
Keywords: Siamang -- Behavior; Whitehanded gibbon -- Behavior; Gibbons; Mammmals -- Indonesia -- Sumatera Utara