WASZCZUK, T.; KUJAWSKA, T.; SOMER, J. C. Focusing of an ultrasonic beam by means of a piezoelectric annular array. Archives of Acoustics, [S. l.], v. 8, n. 3, p. 185–204, 2016. Disponível em: https://acoustics3.ippt.pan.pl/index.php/aa/article/view/3255. Acesso em: 26 apr. 2025.