1. See for example, Nussenzweig, H.M.: Nuclear Phys.11, 499 (1959)
2. Maijer, P.H.E., Repace, J.L.: Am. J. Phys.43, 428 (1975)
3. Taylor, J.R.: Scattering Theory 1st ed. p. 257, New York: John Wiley and Sons 1972
4. Sitenko, A.G.: Lectures in Scattering Theory, 1st ed. p. 124, Oxford: Pergamon Press 1971
5. Schift, L.I.: Quantum Mechanics, 3rd ed. p. 127, New York: McGraw-Hill 1968