1. Backus, M. M.: Dissertation, Massachusetts Institute of Technology 1955
2. de Bièvre, P. J., Debus, G. H.: Nucl. Instr. Methods 32, 224 (1965)
3. Crouch, A. C., Webster, R. K.: J. Chem. Soc. 1963, 118
4. Dalrymple, G. B., Lanphere, M. A.: Potassium-Argon Dating, San Francisco: Freeman & Co. 1969
5. Heumann, K.G., Kubassek, E.: Advances in Mass Spectrometry, Vol. 6, p. 611, Barking/Essex: Applied Science Publishers Ltd. 1974