1. L. D. Landau and E. M. Lifshitz, Course of Theoretical Physics, Vol. 3: Quantum Mechanics: Non-Relativistic Theory, 3rd ed. (Pergamon, New York, 1976), Chap. 6.
2. A. B. Migdal and V. Krainov, Approximation Methods in Quantum Mechanics (W.A. Benjamin, New York, 1969).
3. J. M. Blatt and V. F. Weisskopf, Theoretical Nuclear Physics (Springer, New York, 1979).
4. A. M. Frolov and J. D. Talman, Phys. Rev. A 72, 022511 (2005), Phys. Rev. A 57, 2436 (1998).
5. F. Simkovic, R. Dvornicky, and A. Faessler, Phys. Rev. C 77, 055502 (2008).