1. H. A. VAN DER SLOOT, J. B. LUTEN, private communication, 1976.
2. H. A. VAN DER SLOOT, ECN-1, Petten, Netherlands, 1976.
3. M. K. SHERIF, R. M. AWADALLAH, F. GRASS, J. Radioanal. Chem. (1977) Author, please write the number of the volume and the page.
4. M. K. SHERIF, R. M. AWADALLAH, F. GRASS, J. Radioanal. Chem., (to be published).
5. M. K. SHERIF, R. M. AWADALLAH, F. GRASS, AIAU, 1979.