1. Abramson, L. Y., Seligman, M. E. P. & Teasdale, J. (1978). Learned helplessness in humans: Critique and reformulation. Journal of Abnormal Psychology, 87, 49–74.
2. Asher, S. R., Hymel, S., & Renshaw, P. D. (1984). Loneliness in children. Child Development, 55, 1456–1464.
3. Beck, A. T. (1967). Depression: Causes and treatment. Philadelphia: University of Pennsylvania.
4. Beck, A. T. (1976). Cognitive therapy and emotional disorders. New York: International Universities Press.
5. Beck, A. T., Rush, A. G., Shaw, B. F., & Emery, G. (1979). Cognitive therapy of depression. New York: Guilford Press.