1. See, e.g., R.J. Drachman, Annihilation in gases and galaxies, NASA Conf. Publ. (1989) p. 3058.
2. See, e.g., K.F. Canter, Hyp. Int. 73(1992)159; M. Doyama, T. Akahane and M. Fujinami (eds.), App. Sci. 85(1995) 1–356.
3. See, e.g., J. Eades (ed.),Antihydrogen, Proc. Antihydrogen Workshop, Munich (1992), Hyp. Int. 76 (1993).
4. See, e.g., J.W. Humberston and E.A.G. Armour (eds.),Atomic Physics and Positrons (Plenum, London, 1987).
5. See, e.g., W. Raith and R.P. McEachran (eds.), Hyp. Int. 89(1994);