Queiroz, Emilson França de, et al. “Effect of Planting Date on Soybean Yield in North of Paraná Region, Brazil”. Pesquisa Agropecuaria Brasileira, vol. 33, no. 9, Sept. 1998, pp. 1461-74, doi:10.1590/S1678-3921.pab1998.v33.4981.