1. S.F.J. Cox and R.L. Lichti, J. Alloys Comp., 253–254 (1997) 414–419.
2. See e.g. P. Jena, Treatise on Materials Science and Technology, Vol. 21, Academic Press, New York, 1981, p. 351.
3. E. Karlsson, Solid State Phenomena, Clarendon Press, Oxford, 1995.
4. D. Richter, in Springer Tracts in Modern Physics, Vol 101, 1983.
5. R. Hempelmann and D. Richter, Europhys. News, 22 (1991) 110.