Berlato, M. A., Farenzena, H. and Fontana, D. C. (2005) “Association between El Niño Southern Oscillation and corn yield in Rio Grande do Sul State”, Pesquisa Agropecuaria Brasileira, 40(5), pp. 423–432. doi: 10.1590/S1678-3921.pab2005.v40.6974.