1. G. W. Snedecor and W. G. Cochran, “Statistical Methods,” 6th Ed., The Iowa State Univ. Press, Ames, 1967.
2. M. Miyazaki and S. Hayakawa, “Nutrition of Protein and Amino Acid,” ed. by N. Shimazono and I. Nakagawa, Asakura Shoten, Inc., Tokyo, Japan, 1964, p. 284.