1. Bradford, G. R. and Harding, R. B.: 1957,Proc. Am. Soc. Hortic. Sci. 70, 252.
2. Brewer, R. F., Creveling, R. K., Guillemet, F. B. and Sutherland F. H.: 1960,Proc. Amer. Soc. Hort. Sci. 75, 236.
3. Chapman, H. D. (ed.): 1966,Diagnostic Criteria for Plants and Soils, Univ. Calif. Div. Agr. Sci, Berkeley.
4. Chapman, H. D.: 1968, ‘The Mineral Nutrition of Citrus’, in W. Reuther (ed.)The citrus industry, Vol 11. Univ. Calif. Div. Agr. Sci. Berkeley, 127.
5. Chauhan, R. P. S. and Powar, S. L.: 1978,Plant Soil 50, 145.