PAJEWSKI, W.; KIEŁCZYŃSKI, P.; SZALEWSKI, M. Radiation of piezoelectric rings into the air through cylindrical waveguides. Archives of Acoustics, [S. l.], v. 20, n. 4, p. 361–372, 2014. Disponível em: https://acoustics3.ippt.pan.pl/index.php/aa/article/view/1276. Acesso em: 13 jan. 2025.