Santos, Henrique Pereira dos, et al. “Crop Productivity of Wheat Rotation Systems for Ten-Year Period, in Passo Fundo, RS, Brazil”. Pesquisa Agropecuaria Brasileira, vol. 30, no. 12, Dec. 1995, pp. 1397-02, doi:10.1590/S1678-3921.pab1995.v30.4439.