American Academy of Family Physicians
Family doctor.org: Seasonal Affective Disorder
This article provides great information on Seasonal Affective Disorder, or SAD. The topics that are covered in this article include: what is seasonal affective disorder, How common is SAD, and is there a treatment for SAD.
The National Alliance on Mental Illness
National Alliance on Mental Illness: Depression
This site is a concise page from NAMI describing depression, its causes and symptoms, statistics, treatment, and more.