1. A. Bertin, A. Vitale and A. Placci, La Rivista del Nuovo Cimento, n. 5 (1975) 423.
2. See for example J. Martino, Muon capture in hydrogen, Lecture in this School.
3. H. Primakoff, in: Muon Physics II, Academic Press, Inc., New York, (1975) p. 3.
4. H. Anderhub et al., Phys. Lett. 101B (1981) 151.
5. J. H. Brewer, 8 — Icohepans, Vancouver, Canada (1979).