1. Cox, N. A., B. H. Davis, A. B. Watts and A. R. Colmer, 1970. Unpublished data.
2. Bacteriological Analytical Manual. U.S. Dept. of Health, Education and Welfare;Elliott,1966
3. Poultry Nutrition;Ewing,1963
4. Gastric hydrogen ion concentration and acidity in the domestic fowl;Farner;Poultry Sci.,1943
5. Outlines of Biochemistry;Gortner,1953