Rizzardi, M.A. et al. 2003. Adjustment of model to quantify the effect of weeds and sowing time on soybean yield. Pesquisa Agropecuaria Brasileira. 38, 1 (Jan. 2003), 35–43. DOI:https://doi.org/10.1590/S1678-3921.pab2003.v38.6541.