1. B. Singh and B. C. Verma, J. Sci. Ind. Res.24, 536 (1965).
2. B. Singh and B. C. Verma, J. Ind. Chem. Soc.40, 39 (1963).
3. B. Singh, B. C. Verma, and M. S. Saran, Bull. Chem. Soc. Japan38, 43 (1965).
4. B. Singh, B. C. Verma, and Y. K. Kalia, J. Ind. Chem. Soc.40, 697 (1963).
5. B. Singh and B. C. Verma, Z. analyt. Chem.196, 132 (1963).