Ferrari, J. M. S., C. P. C. Gabriel, T. B. G. Silva, F. D. Mota, L. R. A. Gabriel Filho, and E. M. Tanaka. “ANALYSIS OF THE SPATIAL VARIABILITY OF RESISTANCE TO SOIL PENETRATION AT DIFFERENT DEPTHS”. Revista Brasileira De Engenharia De Biossistemas, vol. 12, no. 2, June 2018, pp. 164-75, doi:10.18011/bioeng2018v12n2p164-175.