1. E. J. Westerman and F. V. Lenel, Trans. AIME 218 (1960) 1010.
2. D. Nobili and R. De Maria, J. Nucl. Matls. 17 (1965) 5.
3. G. F. Missiroli, D. Nobili, and F. Zignani, ibid 21 (1967) 199.
4. R. W. Cahn, in ?Physical Metallurgy?, edited by R. W. Cahn, Chapter 19 (North-Holland, 1965).
5. Second Euratom Quarterly Report, Org. 177/64/4 (1965).