1. Newton, R. G.: Scattering Theory of Waves and Particles. New York: McGraw Hill 1966; see Eq. (12.37) and just below Eq. (12.60)
2. Coester, F.: In: Mathematical, Methods and Applications of Scattering Theory, Proceedings., Washington DC, 1979, (DeSanto, J. A., Saenz, A. W., Zachary, W. W., eds.), Berlin-Heidelberg-New York-Tokyo: Springer 1980
3. Newton, R. G.: Scattering Theory of Waves and Particles, p. 439. New York: McGraw-Hill 1966
4. Reed, M., Simon, B.: Methods of Modern Mathematical Physics, Vol. III: Scattering Theory, pp. 17 and 34. New York: Academic Press 1979
5. Sokolov, S. N.: Sov. Phys. Dokl.22, 198 (1977)