WÓJCIK, Zbigniew Marcin. An acoustical aid for the blind. Archives of Acoustics, [S. l.], v. 4, n. 4, p. 331–346, 1979. Disponível em: https://acoustics.ippt.gov.pl/index.php/aa/article/view/3386. Acesso em: 4 mar. 2026.