1. American Psychiatric Association, 1987. Diagnostic and Statistical Manual of Mental Disorders, third ed. revised. Washington, DC.
2. American Psychiatric Association, 1994. Diagnostic and Statistical Manual of Mental Disorders, fouth ed. Washington, DC.
3. The comprehensive psycchopathological rating scale;Åsberg;Acta Psychiatr. Scand.,1978
4. Cognitive functioning in very old age;Bäckman,1999
5. Aging, behavior, and terminal decline;Berg,1996