I have just ordered Newman's Foundations of Helicopter Flight, as well as Prouty's Helicopter Aerodynamics (the new edition with the three books in one). I will read these, before reading Leishman's again. Then I will consider getting Prouty's bigger book on stability and control. That will keep me busy for a while. To all the parties concerned - Thank you very much for all the advice.
Genghis, if you are still interested in completing your collection, I now have a redundant copy of the original "Helicopter Aerodynamics".
Crab: I am biting my tongue so I wont reply to your post on the flapping & gyroscopic effect. Too much has already been said on that.