1. S. Rapsomanikis, P.J. Craig, Anal. Chim. Acta 248 (1991) 563.
2. J.E. Fergusson, The Heavy Elements: Chemistry, Environmental Impact and Health Effect, Pergamon Press, Oxford, 1990, p. 157.
3. H. Emteborg, E. Bulska, W. Frech, D. C. Baxter, J. Anal. At. Spectrom. 7 (1992) 405.
4. E.P.C. Lai, B. Wong, B.V.A. Vandemoot, Talanta 40 (1993) 1097.
5. J.H. Pavlish, E.A. Sondreal, M.D. Mann, E.S. Olson, K. C. Galbreath, D. L. Laudal, S. A. Benson, Fuel Process. Technol. 82 (2003) 89.