1. G. B. Whitham, Linear and Nonlinear Waves (Wiley, New York, 1974; Mir, Moscow, 1977).
2. V. E. Zakharov, S. V. Manakov, S. P. Novikov, and L. P. Pitaevskii, Theory of Solitons: The Inverse Scattering Method (Nauka, Moscow, 1980; Plenum, New York, 1984).
3. M. Ablowitz and H. Segur, Solitons and Inverse Scattering Theory (SIAM, Philadelphia, PA, United States, 1981; Mir, Moscow, 1987).
4. S. N. Vlasov and V. I. Talanov, Wave Self-Focusing (Institute of Applied Physics, Russian Academy of Sciences, Nizhni Novgorod, 1997) [in Russian].
5. I. A. Molotkov, Analytical Methods in Nonlinear Wave Theory (Fizmatlit, Moscow, 2003; Pensoft, Sofia, 2005).