1. A. S. Bakai and Yu. P. Stepanovskii, Adiabatic Invariants [in Russian], Naukova Dumka, Kiev (1981).
2. M. Born, Lectures on Atomic Mechanics [Russian translation], ONTI, Moscow (1934).
3. L. Schiff, Quantum Mechanics [Russian translation], IL, Moscow (1957).
4. V. P. Maslov, Perturbation Theory and Asymptotic Methods [in Russian], Moscow State Univ. (1965).
5. R. Bott and S. S. Chern, "Hermitian vector bundles and the equidistribution of the zeros of their holomorphic sections," Acta Math.,114, 71?112 (1965).