1. E. L. WYNDER, D. HOFFMAN, Tobacco and Tobacco Smoke, Academic Press, New York, 1967.
2. J. M. A. LENIHAN, Colloque International de Biologie de Saclay, Western Regional Hospital Board, Glaskow Report, 1966.
3. H. STAERK, IAEA Tech. Rep. “Comparative Study of Food and Environmental Contamination”, STI/PUB/348 (1974) 417.
4. T. C. TSO, Botan. Bull. Acad. Sinica, 7 (1966) 28.
5. M. R. GRIFFIN, M. B. HOCKING, D. G. LOWERY, Anal. Chem., 47 (1975) 229.