1. Robinson and collaboratorsPhil. Trans. Roy. Soc. London, 1939,230 B, 149;Biochem. J., 1931, 1687; 1932, 1647; 1933, 206; 1934, 1712.
2. Batesmith..Nature, 1948,161, 835.
3. Wender and collaborators..Analytical Chemistry, 1951,23, 1582.
4. Seshadri and co-workers..Proc. Ind. Acad. Sci., 1936,4 A, 54; 1943,17 A, 26; and 1946,24 A, 352.
5. Rao and Beri.. Ibid., 1951,33 A, 368.