R. W. de Melo, D. C. Fontana, and M. A. Berlato, “Soybean production pointers in Rio Grande do Sul compared to the agricultural zoning”, PAB, vol. 39, no. 12, pp. 1167–1175, Dec. 2004, doi: 10.1590/S1678-3921.pab2004.v39.6892.