1. J. Arends, J. Eyink, A. Hegerath, K. G. Hilger, B. Mecking, G. Nöldeke andH. Rost:Phys. Lett. B,98, 423 (1981);H. Rost: Thesis, University of Bonn (1980).
2. J. Ahrens:Proceedings of International Conference on High Energy Physics and Nuclear Structure, Vancouver, 1979, edited byD. F. Measday andA. W. Thomas: inNucl. Phys. A,335, 167 (1980);
3. B. Ziegler:Proceedings of International Conference on Nuclear Physics with Electromagnetic Interactions, Mainz, 1979, edited byH. Arenhövel andD. Drechsel, inLect. Notes Phys.,108, 148 (1979).
4. E. Oset andW. Weise:Nucl. Phys. A,368, 375 (1981).
5. E. Oset, W. Weise andH. Toki:Phys. Rep. C,83, 282 (1982).