1. R. C. KRONER, Proc. Conf. Traces of Heavy Metals in Water Removal Processes and Monitoring, EPA-902/9-74-001, 1974, p. 311.
2. ASTM, Standard D-1888.
3. S. H. HARRISON, P. D. LA FLEUR, W. H. ZOLLER, Anal. Chem., 47 (1975) 1685.
4. A. VAN DALEN, H. A. DAS, J. LUTEN, H. A. V. D. SLOOT, Trans. Am. Nucl. Soc., 21 (1975) 20.
5. J. R. RHODES, A. H. PRADZYNSKI, et al., Application of Low Energy X- and Gamma-Rays, C. A. ZIEGLER (Ed.) Gordon and Breach, N. Y., 1971, p. 317.