1. F. H. Busse, Rep. Prog. Phys. 41, 1930 (1978); H. L. Swinney, Physica D 7, 3 (1983)
2. G. Ahlers and R. P. Behringer, Phys. Rev. Lett. 40, 712 (1978)
3. P. Bergé and M. Dubois, Contemp. Phys. 25, 535 (1984)
4. J. Boussinesq, C. R. Acad. Sci. (Paris) 72, 755 (1871);
5. D. J. Korteweg and G. de Vries, Philos. Mag. 39, 422 (1895). See also P. G. Drazin and W. R. Reid, Hydrodynamic Stability (Cambridge University, Cambridge, 1981); G. B. Whitham, Linear and Nonlinear Waves (Wiley, New York, 1974)