1. V. Buslaev and A. Fedotov, “The monodromization and Harper equation,” in: Séminaires Equations aux Dérivées Partielles (1993)–(1994), École Polytech., Palaiseau (1994), pp. 1–23.
2. V. Buslaev and A. Fedotov, “Bloch solutions of difference equations,” St. Petersburg Math. J., 7, 561–594 (1996).
3. V. Buslaev and A. Fedotov, “Harper equation: monodromization without quasiclassics,” Algebra Analiz, 8, No. 2, 65–97 (1996).
4. V. Buslaev and A. Fedotov, “On the difference equations with periodic coefficients,” Adv. Theor. Math. Phys., 5, No. 6, 1105–1168 (2001).
5. H. L. Cycon, R. G. Froese, W. Kirsch, and B. Simon, Schrödinger Operators, Springer Verlag, Berlin (1987).