1. A. K. Pogrebkov, “On time evolutions associated with the nonstationary Schrödinger equation,” in: L. D. Faddeev’s Seminar on Mathematical Physics (Amer. Math. Soc. Transl. Ser. 2, Vol. 201, M. Semenov-Tian-Shansky, ed.) (2000), p. 239–255; arXiv:math-ph/9902014v1 (1999).
2. B. B. Kadomtsev and V. I. Petviashvili, Sov. Phys. Dokl., 15, 539–541 (1970).
3. M. Boiti, F. Pempinelli, A. K. Pogrebkov and M. C. Polivanov, Theor. Math. Phys., 93, 1200–1224 (1992).
4. M. Boiti, F. Pempinelli, A. K. Pogrebkov, and M. C. Polivanov, Inverse Problems, 8, 331–364 (1992).
5. M. Boiti, F. Pempinelli, and A. Pogrebkov, J. Math. Phys., 35, 4683–4718 (1994).