Characteristics of hammer stones and anvils used by wild bearded capuchin monkeys (cebus libidinosus) - Visalberghi, Elisabetta; Fragaszy, Dorothy; Ottoni, Eduardo Benedicto; Izar, Patricia; Oliveira, M. G. de; Andrade, Fábio Ramos Dias de (Congress of the International Primatological Society, 2006)