1. Studies of helicopter rotor noise;Lowson;Wyle Laboratories Research Staff WR 68-9,1968
2. Description of a computer program for helicopter noise calculation;Ollerhead;Wyle Laboratories Research Staff WR 68-10,1968
3. Noise characteristics of helicopter rotors at tip speed up to 900 feet per second;Hubbard;J. acoust. Soc. Am.,1960
4. Study to establish realistic acoustic design criteria for future Army aircraft;Sternfield;TREC Technical Report 61-72, U.S. Army Transportation Command, Fort Eustis, Virginia,1961
5. A study of the origin and means of reducing helicopter noise;Cox;TCREC Technical Report 62-73, U.S. Army Transportation Research Command, Fort Eustis, Virginia,1962