1. Halperin, J., Stoughton, R.W., Ketelle, B.H., Lund, T., Brandt, R.: preceeding publication
2. Chuburkov, Yu.T., Maslov, O.D., Lebedev, L.M., Shatalov, V.V., Smirnov, V.Yu., Cuburkova, I.I., Petrov, D.V., Makedonskaya, A.I.: Radiokhimiya16, 827 (1974)
3. Flerov, G.N., Korotkin, Yu.S., Ter-Akopian, G.M., Zvara, I., Oganessian, Yu.Ts., Popeko, A.G., Chuburkov, Yu.T., Chelnokov, L.P., Maslov, O.D., Smirnov, V.I., Gerstenberger, R.: Z. Phys. A ? Atoms and Nuclei292, 43 (1979)
4. Bäcker, H.: Geol. Jb. D17, 151 (1976)
5. See also the recent review: Herrmann, G.: Nature280, 543 (1979)