1. Andersen, E. M., Tipburn of lettuce, Effect of maturity, air and soil temperatures and soil moisture tension. Corn. Un. Agr. Exp. St. Ithaca N.Y. Bull. 829 (1946).
2. Bortner, C. E., Toxicity of manganese to turkish tobacco in acid Kentucky soils. Soil Sci.39, 15?33 (1935).
3. Daji, J. A., Manganese toxicity as a probable cause of the band disease ofAreca palm. Curr. Sc.17, 259?260 (1948); R.A. M.28, 124 (1949).
4. Du Plessis, S. J., Wingerdsiektes in Suid-Afrika Un. of Stellenbosch 1948, 221 p.
5. Fried, M. and Peech, M., The comparative effects of lime and gypsum upon plants grown in acid soils. J. Am. Soc. Agron.38, 614?623 (1946).