D. Cordeiro, J. Sarruge, H. Haag, and G. de Oliveira, “ Concentration of macronutrients in soybean (Glycine max (L.) Merrill) as a function of age, application of phosphorus and of the parts of the plant ”, An. Esc. Super. Agr. Luiz de Queiroz, vol. 37, no. 1, pp. 99–142, Jan. 1980, doi: 10.1590/S0071-12761980000100009.