1. Lin, C. C., The Theory of Hydrodynamic Stability, Cambr. Univ. Press, 1955.
2. Putnam, A. A. and W. R. Dennis, J. Acoust. Soc. Amer.28 (1956) 246.
3. Rayleigh, The Theory of Sound II, McMillan and Co., London, 1940.
4. Grad, H., Commun. Pure Appl. Math.2 (1949) 79.
5. Gunder, D. F., and D. R. Friant, J. Appl. Mech.17 (1950) 327.