1. LE. Garrick and C. E. Watkins, "A Theoretical Study of the Effects of Forward Speed cn the Free-Space Sound-Pressure Around Propellers", NACA Report 1198, 1954.
2. R.A. Arnoldi, "Propeller Noise Caused by Blade Thickness", Report R-0896-1, United Aircraft Research Dept., East Hartford, Conn., 1956.
3. Near field noise of high tip speed propellers in forward flight