1. Drees, J.M.: High speed helicopter rotor design. 19th Annual National Forum, American Helicopter Society (1963).
2. Norman, D.C.; Somsel, J.R.: Determination of helicopter rotor blade compressibility effects — prediction vs. flight test. 23rd Annual National Forum, American Helicopter Society (1967).
3. Tanner, W.H.; Van Wyckhouse, J.F.; Cancro, P.; McCloud III, J.: The helicopter rotor at high Mach numbers. 23rd Annual National Forum, American Helicopter Society (1967).
4. Davenport, F.J.; Front, J.V.: Airfoil sections for helicopter rotors — a reconsideration. 22nd Annual National Forum, American Helicopter Society (1966).
5. Spivey, R.F.: Blade tip aerodynamics — profile and planform effects. 24th Annual National Forum, American Helicopter Society (1968).