1. Zolotov, Yu.A. and Kuz’min, N.M.,Kontsentrirovanie microelementov (Preconcentration of Trace Elements), Moscow: Khimiya, 1982, p. 78.
2. Ishmiyarova, G.R., Shcherbinina, N.I., Sedykh, E.M., Myasoedova, G.V., and Vul’fson, E.K.,Zh. Anal. Khim., 1988, vol. 43, no. 11, p. 1981.
3. Brykina, G.D., Stefanov, A.V., Okuneva, G.A., Alekseeva, N.G., Alekseev, V.A., and Nikitin, Yu.S.,Zh. Anal. Khim., 1984, vol. 39, no. 10, p. 1750.
4. Osnovy analiticheskoi khimii,1996
5. Brykina, G.D., Krysina, L.S., Smirnov, I.P., Kozyreva, G.V., and Bol’shova, G.A.,Zh. Anal. Khim., 1989, vol. 44, no. 12, p. 2181.