Melquiades, Fábio Luiz, Fábio Lopes, Susana Martínez Stagnaro, Mônica Rueda, Paulo Sérgio Parreira, and Carlos Roberto Appoloni. 2009. “Chemical Characterization of Clay SRM by X-Ray Fluorescence – Results Comparison from Different Laboratories”. Semina: Ciências Exatas E Tecnológicas 30 (2):145-50. https://doi.org/10.5433/1679-0375.2009v30n2p145.