Methodology for preparing a reference sample in the air filter matrix. Brazilian Journal of Radiation Sciences, Rio de Janeiro, Brazil, v. 10, n. 2, 2022. DOI: 10.15392/bjrs.v10i2.2037. Disponível em: https://www.bjrs.org.br/revista/index.php/REVISTA/article/view/2037. Acesso em: 24 may. 2025.