1. H. OESCHGER, M. WAHLEN, Ann. Rev. Nucl. Sci., 25 (1975) 423.
2. J. BUSCHMANN, in: Kosmische Strahlung, W. HEISENBERG (Ed.), Springer-Verlag, Berlin, Göttingen, Heidelberg 1953, p. 312.
3. W. HELBIG, S. NIESE, D. BIRNSTEIN, Isotopenpraxis, 20 (1984) 60.
4. V. A. ALEXEEV, V. D. GORIN, T. DIMCHEV, A. L. IVLIEV, I. V. SMIRNOV, N. G. TRIUMFOV, O. S. TSVETSOV, Proc. 2nd Intern. Conf. on Low-Level Counting Vol. 2, High Tatras 1980, Bratislava, 1980, p. 71.
5. W. HELBIG, W. GÖRNER, S. NIESE, Proc. 2nd Intern. Conf. on Low-Level Counting Vol. 1, High Tatras 1980, Bratislava, 1980, p. 277.