1. A.J. Freeman and R.B. Frankel, Hyperfine interactions (Academic Press, New York, 1967).
2. A. Abragam, The theory of nuclear magnetism (Oxford University Press, London, 1961).
3. For a recent survey, see Mössbauer spectroscopy: applications to research in physics, chemistry and biology, ed. B.V. Thosar and P.K. Iyengar (Elsevier, Amsterdam) to be published.
4. H. Frauenfelder and R.M. Steffen, in Alpha-, beta- and gamma-ray spectroscopy, ed. K. Siegbahn, Vol. 2 (North-Holland, Amsterdam, 1965) p. 997.
5. Proc. Int. Topical Meeting on muon spin rotation, Rorschach, 1978, Hyp. Int. 6 (1979) 1.