1. E.N. Iliadou, S.T. Girousi, U. Dietze, M. Otto, A.N. Voulgaropoulos, C.G. Papadopoulos, Analyst 122 (1997) 597.
2. V.K. Gupta, A.K. Jain, L.P. Singh, U. Khurana, Anal. Chim. Acta 31 (1997) 31.
3. U.S. Environmental Protection Agency Site at http//www.epa.gov/safewater/dwh/c-ioc/nickel.html
4. E. Berman, Toxic Metals and Their Analysis, Heyden & Sons, London 1980.
5. Z. Marczenko, Separation and Spectrophotometric Determination of Elements, Ellis Horwood, Chichester, 1986.