B. M. Silva, G. C. de Oliveira, M. E. Serafim, J. J. da Silva Júnior, A. Colombo, and J. M. de Lima, “Accuracy and calibration of capacitance probe in a Rhodic Ferralsol planted with coffee”, PAB, vol. 47, no. 2, pp. 277–286, Apr. 2012.