1. C.S. Gardner, J.M. Green, M.D. Kruskal, R.M. Miura: Phys. Lett. 19, 1095–1097 (1967).
2. NJ. Zabusky, M.D. Kruskal: Phys. Rev. Lett. 15, 240–243 (1965).
3. A. Poincaré: New methods of celestial mechanics, in Selected Works, Vol. I, II (Nauka, Moscow 1971), pp. 1–358.
4. V.E. Zakharov, E.I. Schulman: Physica D1, 191–202 (1980).
5. V.E. Zakharov, E.I. Schulman: Dokl. Akad. Nauk 283, 1325–1328 (1985).