1. Linear and Nonlinear Waves;Whitham,1974
2. Asymptotic Methods in Nonlinear Wave Theory;Jeffrey,1982
3. Hydrodynamic Stability;Drazin,1981
4. Perturbation Methods;Nayfeh,1973
5. Nonlinear wave packets in the Kelvin-Helmholtz instability;Weissman;Philos. Trans. R. Soc. London,1979