1. A. K. Dey, S. C. Srivastava, R. L. Seth, S. N. Sinha, andS. P. Sangal, paper 7-B, VIIth Int. Coord. Chem., Stockholm-Upsala, 1962.
2. S. N. Sinha andA. K. Dey, J. Ind. Chem. Soc.39, 469 (1962).
3. S. P. Sangal andA. K. Dey, J. Ind. Chem. Soc.40, 464 (1963).
4. E. B. Sandell, Colorimetric Determination of Traces of Metals, 2nd Ed. New York: Interscience. 1950.
5. F. D. Snell andC. T. Snell, Colorimetric Methods of Analysis. New York: Van Nostrand. 1928.