Buzetti, Salatiér, et al. “Doses of Zinc in Different Acidity Conditions of a Cerrado Soil. I. Dry Matter and Grain Yield and Soil Critical Level”. Pesquisa Agropecuaria Brasileira, vol. 26, no. 6, June 1991, pp. 913-8, doi:10.1590/S1678-3921.pab1991.v26.3422.