1. P.V. Subba Rao, R.V.S. Murty, B.A.N. Murty, K.S. Murty: Ind. J. Chem. (In press).
2. P.V. Subba Rao, P.S.N. Murty and R.V.S. Murty: J. Inorg. Nucl. Chem.,40, 295 (1978).
3. M.T. Beck, S. Görög: Acta Chim. (Budapest),22, 159 (1960).
4. J. Géher-Glücklich, M.T. Beck: Acta Chim. (Budapest),70, 235 (1971).
5. G. Schwarzenbach: Complexometric Titrations, p. 11. Methuen and Co Ltd., London (1955).