ELLIS, D. Some simple formulae for normal mode wave numbers, cutoff frequencies, and the number of modes trapped by a sound channel. Canadian Acoustics, [S. l.], v. 10, n. 4, p. 7–15, 1982. Disponível em: https://jcaa.caa-aca.ca/index.php/jcaa/article/view/491. Acesso em: 28 feb. 2024.