On Two Formulae for Calculating the Effective Rate of Protection (Notes & Comments). The Pakistan Development Review, [S. l.], v. 12, n. 2, p. pp.189–193, 2022. DOI: 10.30541/v12i2pp.189-193. Disponível em: https://thepdr.pk/index.php/pdr/article/view/311. Acesso em: 10 aug. 2025.