1-J. Berzelius, pogg. America 1826, vol.6, p-369
2-J. Amar.chem.soc.1884, vol.5, p-374, O.W.Gibbs, Acad. 1883, vol.18, p-232
3-O.W.Gibbs, proc.Amer. acad. 1883, vol. 18, p-232
4-F.G.R Giblet, Inorganic chemistry, Butterworth’s, London, 1963, vol. 6, p-420
5-J. Chem. Soc; Dalton Trans; 1978, 283
6-T.Yamase, T. Kiawah, Y. Hash, Y. Masada, J. chem.Soc; chem... comm.; 1979, 697
7- S. K. Roy, R.S Roy, R.Kumar, P.P.Jha, J .Indian chem... soc. 1991, 399
8-S.K. Roy, B.N.Ghosh, J. Indian chem... Soc., 1983, 63
9- CRC Handbook of chemistry and physics, 71st ed.; Lied, D.R., Ed.; CRC Press: Boston, 1990.