1. For a review see for example: Siemssen, R.H.: In: Proceedings of the International Nuclear Physics Conference, Sao Paolo, 1989, vol. 2, p. 569, Hussein M.S. et al. (eds.) Singapore: World Scientific
2. Gonin, M., Coffin, J.P., Guillaume, G., Jundt, F., Wagner, P., Fintz, P., Heusch, B., Malki, A., Fahli, A., Kox, S., Merchez, F., Mistretta, J.: Phys. Rev. C38, 135 (1988)
3. Beck, C., Kovar, D.G., Sanders, S.J., Wilkins, B.D., Henderson, D.J., Janssens, R.V.F., Ma, W.C., Vineyard, M.F., Wang, T.F., Maguire, C.F., Prosser, F.W., Rosner, G.: Phys. Rev. C39, 2202 (1989)
4. Gonin, M., Cooke, L., Hagel, K., Lou, Y., Natowitz, J.B., Schmitt, R.E., Shlomo, S., Srivastava, B., Turmel, W., Utsunomiya, H., Wada, R., Nardelli, G., Nebbia, G., Viesti, G., Zanon, R., Fornal, B., Prete, G., Niita, K., Hannuschke, S., Gonthier, P., Wilkins, B.: Phys. Rev. C42, 2125 (1990)
5. Malki, A., Coffin, J.P., Guillaume, G., Jundt, F., Krishan, K., Rami, F., Wagner, P., Fintz, R., Zahar, M., Gonin, M., Heusch, B., Ohta, M., Rastegar, B., Rebreyend, D., Merchez, F., Mistretta, J., Kox, S.: Z. Phys. A ? Hadrons and Nuclei339, 283 (1991)