1. R. C. Weast, M. J. Astle,Handbook of Chemistry and Physics, 63rd Ed., CRC Press, Boca Raton, 1982, B158.
2. J. W. Mellor,A Comprehensive Treatise on Inorganic and Theoretical Chemistry, Vol. VII, Longmans Green, London, 1947, p. 457.
3. N. Zhou, R. Q. Yu, X. Z. Yao, Z. R. Lu,Talanta 1985,32, 1129.
4. D. M. Shvarts, V. V. Portnova,Zavodsk. Lab. 1958,24, 731.
5. A. R. Denaro, V. J. Occleshaw,Anal. Chim. Acta 1955,13, 239.