C. Rosolem, E. Malavolta, and J. Machado, “ Studies on mineral nutrition of grain sorghum: IX. effects of potassium ”, An. Esc. Super. Agr. Luiz de Queiroz, vol. 37, no. 1, pp. 143–155, Jan. 1980, doi: 10.1590/S0071-12761980000100010.