1. Landau, L. D., Lifshitz, E. M.: Quantum mechanics. Moscow: Fizmatgiz 1963, in Russian.
2. Baz, A. I., Zeldovitch, Ja. B., Perelomov, A. M.: Scattering, reactions and decays in nonrelativistic quantum mechanics. Moscow: Fizmatgiz 1966, in Russian.
3. Ovchinnikova, M. Ja.: JETF49, 275 (1965).
4. Smirnov, B. M.: JETF51, 466 (1966).
5. Komarov, I. V.: Thesis (LGU, 1968), in Russian.