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Shils, M.E., and McCollum, E.V.: The Trace Elements in Nutrition, J. A. M. A. 120: 609, 1940.
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MacLeod, R.A. , and Snell, E.E.: Some Mineral Requirements of Lactic Acid Bacteria, J. Biol. Chem. 170: 351, 1947.
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Sumner, J.B., and Somers, G.F.: Chemistry and Methods of Enzymes, New York, 1947, Academic Press, Inc.
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Martin, D.J. , and Hill, 1. N.: The Evanston Dental Caries Study. V. The Fluorine Content of Saliva and Its Relationship to (A) Oral Lactobacillus Counts and (B) The Prevalence of Dental Caries, J. D. Res . 29: 291, 1950.
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van Ravesteyn, A.H.: Metabolism of Copper in Man, Acta Med. Scandinav. 118: 163, 1944.
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MacPherson, H.T., and Stewart, J.: The Photometric Estimation of Cobalt, J. Biochem. 32: 763, 1938.
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Albert, A., and Gledhill, W.S.: The Choice of a Chelating Agent for Inactivating Trace Metals, J. Biochem. 41: 529, 1947.
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Fosdick, L.S. , Hansen, H.S., and Epple, C.: Enamel Decalcification by Mouth Organisms Suggested Test for Caries Susceptibility, J. A. D. A. 24: 1275, 1937.
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Landy, M., and Dicken, D.M.: A Microbiological Assay Method for Six B Vitamins Using Lactobacillus Casei and Medium of Essentially Known Composition, J. Lab. & Clin. Med. 27: 1082, 1942.
