C. F. de Lima, E. Arnhold, B. L. de Araújo, G. H. Ferreira de Oliveira, and E. A. de Oliveira Júnior, “Evaluation of maize hybrids under three densities in the agricultural frontier in Maranhão State, Brazil”, Com. Sci., vol. 3, no. 1, pp. 30–34, Mar. 2012.