IBRAHIM, M. A.; MELIK, R. W. Optimized sound absorption of a rigid polyurethane foam. Archives of Acoustics, [S. l.], v. 28, n. 4, 2003. Disponível em: https://acoustics3.ippt.pan.pl/index.php/aa/article/view/459. Acesso em: 25 apr. 2025.