References
- Kinsler & Frey, Fundamental of Acoustics (John Wiley & Sons Inc., New York), 1950, 386–91.
- Working papers of the 5th Communications Division meeting of the International Civil Aviation Organization (I.C.A.O.), Montreal, 1954.
- Pender, McIlwain, Electrical Engineers' Hand book: Electric Communication & Electronics (John Wiley & Sons Inc., New York), 1950, 9–24 to 9–29.