1. E. K. Sklyanin, ?The inverse scattering method and the quantum nonlinear Schrödinger equation,? Dokl. Akad. Nauk SSSR,244, 1337 (1979).
2. E. K. Sklyanin, L. A. Takhtadzhyan, and L. D. Faddeev, ?The quantum inverse scattering method,? Teor. Mat. Fiz.,40, 194 (1979).
3. L. D. Faddeev, ?Quantum completely integrable field theory models,? Preprint R-2-79 [in Russian], Leningrad Branch, V. A. Steklov Mathematics Institute (1979);
4. L. D. Faddeev, ?Quantum completely integrable field theory models,? in: Problems of Quantum Field Theory (Proc. Fifth International Symposium on Nonlocal Field Theories, Alushta, 1979) [in Russian], JINR, Dubna (1979), p. 249.
5. E. K. Sklyanin, ?On complete integrability of the Landau-Lifshitz equation,? Preprint E-3-79, Leningrad Branch, V. A. Steklov Mathematics Institute (1979).