Orangutans' color preference for food items

This publication has 3 references indexed in Scilit:

• Principles and practice in formulating manufactured animal foods in the UK
  International Zoo Yearbook, 1976
• The behaviour and ecology of wild orang-utans (Pongo pygmaeus)
  Animal Behaviour, 1974
• The Behaviour of Free-living Chimpanzees in the Gombe Stream Reserve
  Animal Behaviour Monographs, 1968