You can try here
http://www.nimh.nih.gov/health/topics/depression/men-and-depression/index.shtml
but nothing will help if he won't admit it or if he doesn't want help. Some people get accustomed to the darkness and getting out is too scary. Good luck, you are kind to try to help. Personally I wouldn't bother, mine claims depression now and then, whatever, he certainly never helped me, I'll return the favor