1. Rowcliffe, A. F., et al., UKAEA, TRG Report 1283 (C) (1966).
2. Fraser, A. S., Birss, I. R., and Cawthorne, C., Nature, 211, 291 (1966).
3. Birss, I. R., Nuclear Eng., 10, 465 (1965).
4. Barnes, R. S., and Mazey, D. J., Proc. Roy. Soc., A, 275, 47 (1963).
5. Brown, L. M., and Mazey, D. J., Phil Mag., 10, 1081 (1964).