1. Head, J., “Modern Dentistry”, second ed., 43 (W. B. Saunders Co., Philadelphia, 1920).
2. Bunting, R. W., and Rickert, V. G., J. Amer. Dent. Assoc., 252 (1915); 519 (1918).
3. Ruthrauff, W. M., “Landmarks in Dental Research Leading to the Establishment of the Calcification Theory of Immunity of Dental Caries” (W. M. Ruthrauff Co., Philadelphia, Pa., 1923). Pamphlet Volume 3315, Army Med. Libr., Washington, No. 378421.
4. Caldwell, R. C., Muntz, M. L., Gilmore, R. W., and Pigman, W., J. Dent. Res., 36, 732 (1957).
5. Newbrun, E., Timberlake, P., and Pigman, W., J. Dent. Res., 38, 293 (1959).