1. V. I. Arnol’d, V. V. Kozlov, and A. I. Neishtadt, “Mathematical aspects of classical and celestial mechanics,” in Itogi Nauki Tekh. Ser. Sovrem. Probl. Mat. Fundam. Napravleniya, Vol. 3: Dynamical Systems – 3 (VINITI, Moscow, 1985), pp. 5–290.
2. H. Cycon, R. Fröse, W. Kirsch, and B. Saimon, Schrödinger Operators with Applications to Quantum Mechanics and Global Geometry (Springer- Verlag, Berlin–Heidelberg, 1987).
3. F. G. Gustavson, “On constructing formal integrals of a Hamiltonian system near an equilibrium point,” Astron. J. 71, 670–686 (1966).
4. V. P. Maslov, Perturbation Theory and Asymptotic Methods (Izd. Moscow Univ., Moscow, 1965) [in Russian].
5. M. V. Karasev and V. P. Maslov, “Asymptotic and geometric quantization,” Russian Math. Surveys 39 (6 (240)), 133–205 (1984).