1. ASHKAR, S.A. and S.K. RIES. 1971. Lettuce tipburn as related to nutrient imbalance and nitrogen composition. J. Amer. Soc. Hort. Sci. 96:448–452.
2. BANGERTH, F. 1979. Calcium-related physiological disorders of plants. Annu. Rev. Phytopathol. 17:97–122.
3. BANKO, T.J. and A.A. BOE. 1975. Effects of pH, temperature, nutrition, ethephon and chlormequat on endogenous cytokinin levels of Coleus blumei Benth. J. Amer. Soc. Hort. Sci. 100:168–172.
4. BARBER, S.A. and S.M. ELGAWHARY. 1974. Plant nutrient absorption from three sources in soil. Trans. 10th Intern. Congr. Soil Sci. (Moscow) IV:217–223.
5. BEDI, A.S. and G.S. SEKHON. 1977. Effect of potassium and magnesium application to soils on the dry-matter, yield and cation composition of maize. J. Agr. Sci. (Camb.) 88:753–758.