1. G. Barbiellini, M. Conversi, M. Grilli, A. Mulachié, M. Nigro, L. Paoluzi, P. Spillantini, R. Visentin and G. T. Zorn: Frascati report LNF-70/38 (1970);
2. B. Bartoli, B. Coluzzi, F. Felicetti, G. Goggi, G. Marini, F. Massa, D. Scannicchio, V. Silvestrini and F. Vanoli: Nuovo Cimento, 70 A, 615 (1970);
3. V. E. Balakin, G. I. Budker, I. B. Vasserman, O. S. Koifman, L. M. Kurdadge, S. I. Mismnev, A. P. Onnuchin, S. I. Seredryakov, V. A. Sidorov, A. N. Skrinsky, G. M. Tumaikin, V. F. Turkin, A. G. Khabakhpashev and J. M. Smatunov: Novosibirsk report 62/70, (1970); see also the Rapporteur talk by R. Wilson: in the Proceedings of the International Conference on High-Energy Physics (Kiev, 1970).
4. See invited talk by μπ group in the Proceedings of the International Conference of E.P.S. on Meson Resonances and Related Electromagnetic Phenomena (Bologna, 1971).
5. B. Borgia, M. Conversi, M. Grilli, E. Iarocci, M. Nigro, L. Paoluzi, P. Spillantini, L. Trasatti, V. Valente, R. Visentin and G. T. Zorn: Frascati report LNF-71/62 (1971).