1. J. H. WERNICK and S. GELLER,MS Trans. AIME 218 (1960) 866.
2. A. E. CLARK,AIP Proc. 18 (1973) 1015.
3. W. E. WALLACE, ?Rare Earth Intermetallics? (Academic Press, New York and London, 1973).
4. K. N. R. TAYLOR and M. I. DARBY, ?Physics of Rare Earth Solids? (Chapman and Hall, London, 1972).
5. K. N. R. TAYLOR,Adv. Phys. 20 (1971) 551.