Ainsworth, M.D. et. al. (1962). Deprivation of maternal care: A reassessment of its effects. Org., Geneva: World Health.
Bandura, A. (1969). Principles of behavior modification. N.C.: Holt.
Bandura, A. y Walters, R.H. (1963). Social learning and personality development. N.Y.: Holt.
Bertalanffy, L. von (1967). Robots, men and minds: Psychology in the modern world. N.Y.: George Braziller.
Buytendijk, F.J.J. (1952). Traité de Psychologie animale. París: P.U.F.
Callens, M. (1972). Psychofysiologie. Deel 4. Psychofysiologie van motivatie en emotie. Leuven: Acco.
Darwin, C. (1872). Expression of the emotions in man and animals. London: Murray.
Eysenck, H.J. (1960). The Structure of human personality. London: Methuen