Sugawara, L.M., Rudorff, B.F.T. and Adami, M. (2009) “Feasibility of the use of Landsat imagery to map soybean crop areas in Paraná, Brazil”, Pesquisa Agropecuaria Brasileira, 43(12), pp. 1777–1783. doi:10.1590/S1678-3921.pab2008.v43.1053.