1. American Psychiatric Association (APA). (2000). Diagnostic and statistical manual of mental disorders (4th ed., Text Revision). Washington, DC: Author.
2. Avery, D. H., Dahl, K., Savage, M. V., Brengelmann, G. L., Larsen, L. H., & Kenny, M. A. (1997). Circadian temperature and cortisol rhythms during a constant routine are phase-delayed in hypersomnic winter depression. Biological Psychiatry, 41, 1109–1123.
3. Beck, A. T., Rush, A. J., Shaw, B. F., & Emery, G. (1979). Cognitive therapy of depression. NY: Guilford Press.
4. Beck, A. T., Steer, R. A., & Brown, G. (1996). Manual for the Beck Depression Inventory-II. San Antonio, TX: Psychological Corporation.
5. Blazer, D. G., Kessler, R. C., & Swartz, M. S. (1998). Epidemiology of recurrent major and minor depression with a seasonal pattern. The National Comorbidity Survey. British Journal of Psychiatry, 172, 164–167.