Reference
- Rosenblith , W. A. and Stevens , K. N. 1953 . The Staff of Bolt, Beranek and Newman Handbook of Acoustic Noise Control. . Noise and Man. , Volume 11 June : 219
- Beranek Leo , L. 1960 . Noise Reduction. , 1st Ed. , 498 New York, N. Y. : The McGraw-Hill Book Company, Inc. .