1. V. C. Howard, C. Harvey, R. P. Thorne, andA. J. Morgan,TRG Report 1772 (C) (1969).
2. R. P. Thorne andV. C. Howard,Proc. Brit. Cer. Soc,7 (1967) 449.
3. H. Kronberger,J. Nuclear Materials 14 (1964) 4.
4. H. A. Pearl, J. M. Nowak, andH. G. Deban,WADC Technical Report (1960) 59.
5. J. C. Rumsey andA. C. Roberts,Proc. Brit. Cer. Soc. 7 (1967) 233.