Kasper, S et al.  The effects of light therapy in treatment indications other than seasonal affective disorder (SAD).  in Holick MF, Jung EG (eds): Biologic Effects of Light 1993. Berlin, Walter de Gruyter; 1994:206-218; Eastman, CI et al.  Bright light treatment of winter depression.  Arch Gen.Psychiatry. 1998;883-889.