1. T. Ikebe, Arch. Rat. Mech. Anal. 5(1) (1960);
2. T. Ikebe, Pacific. J. Math. 15(511) (1965)
3. A. Bohm, Quantum Mechanics: Foundations and Applications, 3rd edn. (Springer, Berlin, 1993), p. 433
4. C. Cohen-Tannoudji, B. Diu, F. Laloë, Quantum Mechanics (Wiley-VCH, New York, 1977), vol. 2, p. 910
5. L.S. Rodberg, R.M. Thaler, Introduction to the Quantum Theory of Scattering (Academic Press, New York, 1967), p. 6