1. V. E. Zakharov and S. V. Manakov, “Exact theory of resonant interaction of wave packets in nonlinear media,” INF Preprint No. 74-41, Inst. Nuclear Physics, Siberian Branch, USSR Acad. Sci., Novosibirsk (1975)
2. V. E. Zakharov and S. V. Manakov, Soviet Phys. JETP, 42, 842–850 (1975).
3. V. E. Zakharov, S. V. Manakov, S. P. Novikov, and L. P. Pitaevskii, Theory of Solitons: The Inverse Scattering Method [in Russian], Nauka, Moscow (1980); English transl.: S. P. Novikov, S. V. Manakov, L. P. Pitaevskii, and V. E. Zakharov, Plenum, New York (1984).
4. V. E. Zakharov and A. B. Shabat, Funct. Anal. Appl., 8, 226–235 (1974); 13, 166–174 (1979).
5. L. A. Takhtadjan and L. D. Faddeev, Hamiltonian Method in the Theory of Solitons [in Russian], Nauka, Moscow (1986); English transl.: L. D. Faddeev and L. A. Takhtadjan, Springer, Berlin (1987).