1. S. V. Manakov, Zh. Eksp. Teor. Fiz. 67, 543–555 (1974).
2. G. Sh. Guseinov, Dokl. Akad. Nauk 231, 1045–1048 (1976).
3. I. M. Guseinov and Ag. Kh. Khanmamedov, Teor. Mat. Fiz. 119, 429–440 (1999).
4. G. Teschl, Jacobi Operators and Completely Integrable Nonlinear Lattices (Am. Math. Soc., Providence, RI, 2000).
5. Ag. Kh. Khanmamedov, Mat. Sb. 199(10), 137–160 (2005).