Cruscil, Carlos Alexandre Costa, et al. “Nutrients Concentrations in the Flag Leaf and Grains of Black-Oat Affected by Phosphate and Potassium Fertilization”. Semina: Ciências Agrárias, vol. 30, no. 4, Dec. 2009, pp. 833-40, doi:10.5433/1679-0359.2009v30n4p833.