Wisan, J.M.: Dental Caries and Fluorine-Water, Public Health News (NJ. Dept. of Health, Trenton, N. J.). 27: 139, 1944.
2.
Fisher, R.A., and Yates, F.: Statistical Tables for Biological, Agricultural and Medical Research, ed. 3, New York, 1949 , Hafner Publishing Company, Inc., p. 32.
3.
Mainland, D.: Elementary Medical Statistics, Philadelphia, 1952, W. B. Saunders Company, p. 311.
4.
Ostrander, F.D. , Crowley, M.C., and Dowson, J.: A Clinical Study of the Treatment of Root Canal and Periapical Infections with Penicillin, J. D. Res . 26: 403, 1947.
5.
Fisher, R.A.: Statistical Methods for Research Workers, ed. 11, New York, 1950, Hafner Publishing Company, Inc., pp. 92-94.
6.
Statistical Research Group, Columbia University: Selected Techniques of Statistical Analysis, New York, 1947 , McGraw-Hill Book Company, Inc., p. 266.
7.
Statistical Research Group, Columbia University: Selected Techniques of Statistical Analysis, New York, 1947, McGraw-Hill Book Company, Inc., chapt. 16.
