1. Hughes, D. J., Schwartz, R. B.: BNL-325, Brookhaven National Laboratory, USAEC, 1958
2. Joshi, B. D., Patel, B. M.: Appl. Spectroscopy 24, 573 (1970)
3. Joshi, B. D., Patel, B. M., Page, A. G.: Anal. Chim. Acta 57, 379 (1971)
4. Lederer, C. M., Hollander, J. M., Perlman, I.: Table of isotopes, Sixth edition. New York: John Wiley & Sons 1967
5. Mathews, C. K.: J. Sci. Ind. Res. 30, 297 (1970)