1. Rayleigh, Lord 1887 Proc. Lond. Math. Soc. 19,67
2. see also Lord Rayleigh, The Theory of Sound, 368, Dover Publications, New York (1945).
3. Miles, J. W. 1963 J. Fluid Mech. 16,209.
4. Howard, L. N. 1961 J. Fluid Mech. 10,509.
5. Goldstein, S. 1931 Proc. Roy. Soc. A,132,524.