1. R.L. Mössbauer, Z. Phys. 151(1958)124.
2. H.J. Lipkin, reproduced in:The Mössbauer Effect, ed. H. Frauenfelder (Benjamin, New York, 1963) p. 13.
3. L.L. Lee, Jr., L. Meyer-Schützmeister, J.P. Schiffer and D. Vincent, Phys. Rev. Lett. 3(1959)223.
4. P.P. Craig, J.G. Dash, A.D. McGuire, D. Nagle and R.R. Reiswig, Phys. Rev. Lett. 3(1959)221.
5. H.J. Lipkin, in:Nuclear Zeeman Effect and Recent Advances in Mössbauer Spectroscopy, Proc. Int. Workshop in Honor of Professor S.S. Hanna, ed. P. Boolchand, Stanford University, 15 March 1991, p 3; Hyp. Int. 72(1992)3.