1. Crighton, D.G., Ffowcs Williams, J.E., and Cheeseman, I.C. 1976 AIAA Paper 76-530 (to appear in J. Aircraft 1977).
2. Bechert, D., and Pfizenmaier, E. 1975 J. Sound Vib, 43, 581
3. Moore, C.J. 1977 J.Fluid Mech. 80, 321.
4. McLaughlin, D.K. Morrison, G.L., and Troutt, T.R. 1975 J. Fluid Mech, 69, 73.
5. Tam, C.K.W. 1972 J.Fluid Mech, 51, 69.