Fontes, Renildes Lucio Ferreira, et al. “Bioavailability of Soil Cu, Fe, Mn and Zn from Soil Fractions”. Semina: Ciências Agrárias, vol. 42, no. 1, Jan. 2021, pp. 19-42, doi:10.5433/1679-0359.2021v42n1p19.