If anyone ever finds a source for Ray Prouty's Helicopter Aerodynamics etc books, please let me know. I have two of them on loan from a friend - but I'll have to give them back some day.
Absolutely brilliant, and he explains most of it with hardly any maths, for the non-technical amongst us. I've trawled 2nd hand book websites, but never found any copies.
Other than that I can't recommend much that hasn't already been mentioned, except to say that without "The Art and Science..." I don't think I'd have passed my CPL Principles of Flight - thank you Shawn.