ENGEL, Zbigniew. K.U. INGARD, Notes on Sound Absorption Technology, Noise Control Foundation, Poughkeepsie. Archives of Acoustics, [S. l.], v. 21, n. 1, p. 115–117, 1996. Disponível em: http://acoustics.ippt.gov.pl/index.php/aa/article/view/984. Acesso em: 18 apr. 2026.