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2. Clarke, S. K. R., Daigleish, P. G., and Gillespie, W. A. (1952). Ibid., 1, 1132.
3. Fairbrother, R. W., Martyn, G., and Parker, L. (1951). Ibid., 2, 516.
4. Forbes, G. B. (1949). Brit. med. J., 2, 569.
5. Horton, B. F., and Knight, V. (1955). J. Tenn. med. Ass., 48, 367.