1. L. D. Landau, Phys. Zs. Sovietun. 1, 88 (1932); Collected Works, Vol. 6.
2. R. Serber, Phys. Rev. 72, 1008 (1947).
3. K. Alder and A. Winther, Electromagnetic Excitation (North-Holland, Amsterdam, 1975).
4. A. G. Sitenko, Theory of Nuclear Reactions (Energoatomizdat, Moscow, 1983; World Sci., Singapore, 1990).
5. C. A. Bertulani and G. Baur, Phys. Rep. 163, 299 (1988).