1. T. Westermark, B. Sjöstrand,Intern. J. Appl. Radiation Isotopes, 9 (1960) 63.
2. C. M. Lederer, J. M. Hollander, I. Perlman, Table of Isotopes, 6th Ed., John Wiley and Sons Inc., New York.
3. R. C. Hawkins, W. J. Edwards, E. M. Leod, AEC, CRDC-1006, March 1961.
4. C. E. Crouthamel, Applied Gamma-ray Spectrometry, Pergamon Press, New York, 1960.
5. G. Friedlander, J. W. Kennedy, J. M. Miller, Nuclear and Radiochemistry, 2nd Ed., John Wiley and Sons Inc., New York 1964.