Campos, Rogério Costa, José Alexandre M. Demattê, and Carlos Fernando Quartaroli. 2003. “Indirect Determination of Hematite Content in Soil from Colorimetric and Radiometric Data”. Pesquisa Agropecuaria Brasileira 38 (4):521-28. https://doi.org/10.1590/S1678-3921.pab2003.v38.6602.