1. E.H.S. Burhop, in High energy physics, vol. 3, ed. E.H.S. Burhop (Academic Press, New York, 1969) p. 103; L.I. Ponomarev, in High energy physics and nuclear structure, 1975 (Santa Fe and Los Alamos) AIP Conf. proc. no. 26, ed. D.E. Nagle et al. (AIP, New York, 1975) p. 563; H. Daniel, Proc. of the Int. Symp. on meson chemistry and mesomolecular processes in matter, Dubna, June 7?10, 1977, to be published.
2. J.D. Knight, C.J. Orth, M.E. Schillaci, R.A. Naumann, H. Daniel, K. Springer and H.B. Knowles, Phys. Rev. A 13 (1976) 43.
3. P. Vogel, P.K. Haff, V. Akylas and A. Winther, Nucl. Phys. A254 (1975) 445.
4. T. Dubler, K. Käser, B. Robert-Tissot, L.A. Schaller, L. Schellenberg and H. Schneuwly, Phys. Lett. 57A (1976) 325; H. Schneuwly, Proc. of the Int. Symp. on meson chemistry and mesomolecular processes in matter, Dubna, June 7?10, 1977, to be published.
5. W.H. Gardner and H. Weinberger, in Anorganic syntheses, vol. 1, ed. H.S. Booth (McGraw-Hill, New York, 1939) p. 84.