1. Ekman, P. (1972). Universals and cultural differences in facial expressions of emotion. In J. Cole (Ed.),Nebraska symposium on motivation, 1971 Lincoln: University of Nebraska Press.
2. Ekman, P. (1973).Darwin and facial expression. New York: Academic Press.
3. Ekman, P. (1977). Biological and cultural contributions to the body and facial movement. In J. Blacking (Ed.),The anthropology of the body. London: Academic Press.
4. Ekman, P., & Friesen, W. V. (1971). Constants across cultures in the face and emotion.Journal of Personality and Social Psychology, 17, 124?129.
5. Ekman, P., and Friesen W. V. (1975).Unmasking the face. Englewood Cliffs, N. J.: Prentice Hall.