1. K. K. S. PILLAY et al., Anal. Chem., 43 (1971).
2. R. LITMAN, H. L. FINSTON, E. T. VILLIAMS, Proc. on Nuclear methods in Environmental Research, Columbia, Missouri, 1974.
3. R. E. JERVIS, B. HEFENBACH, Proc. on Nuclear Methods in Environmental Research, Columbia, Missouri, 1971, p. 188.
4. G. WESTOO, Chemical Fallout, Chapter 5, 1969, p. 75.
5. I. D. PEARCE, R. R. BROOKS, R. D. REEVES, J. AOAC, 59 (1976) 655.