1. L. U. JOSHI, A. K. GANGULY, Curr. Sci., 41 (1972) 762.
2. L. U. JOSHI, A. K. GANGULY, Proc. of Symp. on Isotope Ratios as Pollutant Source and Behaviour Indicators, Vienna, Austria, IAEA/SM-191/3, 1975, p. 169.
3. V. V. CHERDYNTSEV et al., Tr. III, Sessii Komissi po Opredeleniyn Absolyntnogo Voziasta: Izd. Akad. Nauk. USSR, Moscow (Proc. III Session, Committee for Determination of Absolute Age, 1955, p. 175.
4. I. E. STARIK, F. E. STARIK, V. A. MIKHAILOV, Geochem., (1958) 587.
5. P. I. CHALOV, Geochem., (1959) 203.