Marenco, Ricardo Antonio, and Ávila Maria Bastos Santos. “Crop Rotation Reduces Weed Competition and Increases Chlorophyll Concentration and Yield of Rice”. Pesquisa Agropecuaria Brasileira, vol. 34, no. 10, Oct. 1999, pp. 1881-7, doi:10.1590/S1678-3921.pab1999.v34.5506.