H. de O. Feitosa, G. C. FARIAS, R. J. costa Silva Junior, F. jardelson ferreira, F. L. Andrade Filho, and C. F. Lacerda, “Influence of potassium fertilization and borácica performance Sunflower”, Com. Sci., vol. 4, no. 3, pp. 302–307, Oct. 2013.