1. Cheema K S and Pandey R K 1980 J. Nucl. Agric. Biol. 9, 41–45.
2. Coombs J 1978 UNEP Training Course (Madurai).
3. Deshpande R G and Nimbalkar J D 1980 Geobios 7, 91–92.
4. Hegde B A and Patil T M 1981 Photosynthetica 15, 1–4.
5. Hume D J and Criswell J G 1973 Crop. Sci. 13, 519–524.