1. Boxwell, D. A. and Schmitz, F. H. “In-Flight Acoustic Comparison of the 540 and K747 Main Rotors for the AH-1S Helicopter,” Appendix, U. S. Army Aviation Engineering Flight Activity Report 77–88, Edwards AFB, CA, 1979
2. Boxwell, D. A. and Schmitz, F. H. “Full-Scale Measurements of Blade-Vortex Interaction Noise,” J. Am. Helicopter Soc27, No.4, Oct. 1982.
3. Boxwell, D. A., Yu, YH. ., and Schmitz, F. H. “Hovering Impulsive Noise: Some Measured and Calculated Results,” NASA CP-2052,1978; also Vertica, 3, No. 1, 1979.
4. 4]Caradonna, F. X. “The Transonic Flow on a Helicopter Rotor,” Ph.D. dissertation, Stanford Univ., Stanford, CA, 1978.
5. Caradonna, F. X. and Isom, M. P. “Numerical Calculations of Unsteady Transonic Potential Flow Over Helicopter Rotor Blades,” AIAA J.14, No. 4 (1976), 482–88