1. Beattie, C. P. (1955). Proc. Roy. Soc. Med. In the press.
2. Ball, J. D., Williams, A. W., and Davies, J. N. P. (1954). Lancet, 1, 1049.
3. Bedford, D. E., and Konstam, G. L. S. (1946). Brit. Heart J., 8, 236.
4. Bengtsson, E. (1950). Cardiologia, 17, 289.
5. Beverley, J. K. A., Skipper, E., and Marshall, S. C. (1955). Brit. med. J., 1, 577.