1. Allen, F. H., and Kellner, Ashworth, J., and Motto, A. S. (1947). Amer. J. A. (1947). New
2. Bernstein, T. C., and Wolff, H. G. (1950). Ann. intern. Med., 33, 1120.
3. Coogan, T. J., Martinson, D. L., and Mathews, W. H. (1945). Illinois med. J., 87, 296.
4. Creaturo, N. E. (1950). J. Amer. med. Ass., 143, 234.
5. Crowther, J. S. (1951). Brit. med. J., 2, 775.