Original: How Stuff Works: "How Caffeine Works" Erowid Caffeine Vaults Highly Caffeinated: The Caffeine Information Archive" National Geographic January 2005: Caffeine Caffeine Zone: Social and Medical info on caffeine and its effects.
Simplified: The Effects Of Caffeine Addiction Caffeine: How Stuff Works National Geographic January 2005 Erowid Caffeine Vaults #caffeine!