The Emperor Wears No Clothes:
Cannabis and the Conspiracy Against Marijuana
By Jack Herer
This is the book that almost single-handedly revived the Hemp movement in America. Every page of Jack Herer's classic book is filled with information and historical documentation about the demonized weed Marijuana. From USDA documents to congressional records, this is the place to start if you want to understand the history, evolution, and prohibition of Hemp as a renewable natural resource.
This book is a must buy, but it's also available on-line from http://www.jackherer.com/chapters.html for those interested in further research.