1. AMOS, H. E., BRIGDEN, W. D., and MCKERRON, R. A. (1975) Brit. med. Y., I, 598
2. Cited by;BEUTNER, E.H.,1973
3. Brit;BROWN, P.; BADDELEY, H.; READ, A.E.; DAVIES, J.D.; MCGARRY, J.;K; Trans,1974
4. Brit;Lancet, I, 334 RAFTERY, E. B., and DENMAN, A. M. Brit. med. RAHI, A. H. S., and GARNER, A. (In preparation) SAMS, W. M., and JORDAN, R. E. TAYLOR, C. R., and BURNS, J. WINDSOR, W. O., KURREIN, F., and DYER, N. F. WRIGHT, P.;J; Surv,1975