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3. Carter, E. P., and Dieuaide, F. R. (1923). Joh/i Hopkins Hosp. Bull., 34, 401.
4. Comeau, W. J. (1937). Amer. J. med. Sci., 194, 43.
5. Duras, P. F. (1944). Brit. Heart J., 6, Gilchrist, A. R. (1937). Brit. med. J., 1, 203.