1. Ahmed, H.M., Lombeck, I., El-Karib, A.O., El-Amin, E.O., Menzel, H., Frosch, D., Leichsenring, M., and Bremer, H.J. (1989) J.Trace Elem. Electrolytes Health Dis. 3, 171–174.
2. Ahmed, H.M., Laryea, M.D., El-Karib, A.O., El-Amin, E.O., Biggemann, B., Leichsenring, M., Mayatepek, E., and Bremer, H.J. (1990) Z. Ernährungswiss. 29, 47–53.
3. Bieri, J.G., Tolliver, T.J., and Catignani, G.L. (1979) Am.J.Clin.Nutr. 32, 2143–2149.
4. Farrell, P.M., Levine, S.L., Murphy, M.D., and Adams, A.J. (1978) Am.J.Clin.Nutr. 31: 1720–1726.
5. Flohé, L., and Günzler, W.A. (1984) Methods Enzymol. 105, 91–107.