1. A. G�tz undH. Bober, Z. analyt. Chem.187, 92 (1961).
2. A. P. Terentev, A. M. Turkeltaub, E. A. Bondarevskaja undL. A. Domotschkina, Dokl. Akad. Nauk SSSR148, 1316 (1963).
3. L. V. Kuznetsova, E. N. Stoljarova undS. L. Dobytschin, ?. anal. chim. SSSR20, 836 (1965).
4. G. Pippel undS. R�mer, Mikrochim. Acta [Wien]1966, 1036.
5. F. Ehrenberger undO. Weber, Mikrochim. Acta [Wien]1967, 513.