This list will be expanded, but there is one book I recommend more than any other: Norman DeWitt's "Epicurus and His Philosophy."
I have blogged about professor DeWitt at NewEpicurean.com frequently.
Copies of "Epicurus And His Philosophy" can be found through Abebooks here.
A summary of Professor DeWitt's perspective on Epicurus can be found in his essay "Philosophy for The Millions."
In addition to Norman DeWitt:
- The Greeks on Pleasure - Gosling & Taylor