Santos, H.P. dos et al. 1991. Crop rotation in Guarapuava. X. Effects of winter crops on some agronomic characteristics of soybean plants under direct drilling. Pesquisa Agropecuaria Brasileira. 26, 9 (Sep. 1991), 1551–1561. DOI:https://doi.org/10.1590/S1678-3921.pab1991.v26.3497.