Echer, F.R. et al. 2009. Potassium sources in covering fertilization on cotton I – Yield, fiber quality and economic analisys. Semina: Ciências Agrárias. 30, 4Sup1 (Dec. 2009), 1135–1144. DOI:https://doi.org/10.5433/1679-0359.2009v30n4Sup1p1135.