1. Folin, O., and Wu, H. (1920). J. biol. Chem., 41, 367.
2. Harding, V. J., and Downs, C. E. (1933). J. biol. Chem., 101, 487.
3. Haslewood, G. A. D., and Strookman, T. A. (1939). 33, 920.
4. Micro-Analysis in Medical Biochemistry;J., Biochem; King, E.J.,1947
5. King, E. J., Haslewood, G. A. D., and Grant, G. A. (1936). Nature, 137, 872.