1. G. HARBOTTLE, in: A Specialist Periodical Report “Radiochemistry” Vol. 3, Burlington House, London, 1976, p. 33.
2. I. KULEFF, R. DJINGOVA, Proc. National Symp. Fizitschni metodi za otkrivane, izsledvane i opazvane na pametnitzite na kulturata (Physical Methods for Discovery, Investigation of Cultural Monuments), Sofia-1981 (in press).
3. E. V. SAYRE, R. W. SMITH, Science, 133 (1964) 1824.
4. E. V. SAYRE, Proc. 7th Congress on Glass, Brussels-1965, Rep. 220, Gordon and Breach, New York, 1966.
5. R. F. COLEMAN, Proc. Conf. Modern Trends in Activation Analysis, Vol. 2, 1968, p. 1362.