Ortiz, F. R., Brito, O. R., Borkert, C. M., & Brito, R. M. (2005). Proceedings for extracts obtaining and micronutrients determination in soil samples. Semina: Ciências Agrárias, 26(1), 49–52. https://doi.org/10.5433/1679-0359.2005v26n1p49