1. Bragg, W. L., Atomic Structure of Minerals: 226 (1937).
2. BURNS, C.M., BIOCHEM J 29: 2385 (1935).
3. BURNS, C.M., BIOCHEM J 30: 1207 (1937).
4. EISENBERGER, S, CHEMICAL REVIEWS 26: 257 (1940).
5. Hoffman, A. E., Journal of the Association of Official Analytical Chemists 25: 206 (1942).