1. Adams, M. J., Kirkbright, G. F., Rienvatana, P.: At. Absorpt. Newsl. 14, 105 (1974)
2. Barnard, W. M., Fishman, M. J.: At. Absorpt. Newsl. 12, 118 (1973)
3. Barnett, W. B.: Anal. Chem. 44, 695 (1972)
4. Briese, L. A., Giesy, J. P.: At. Absorp. Newsl. 14, 133 (1975)
5. Ciaccio, L. L.: Water and water pollution handbook, Vol. 4. New York: Marcel Dekker 1973