SCHUHMACHER, W. W. . Research on the Physiological Correlate to the two Vowel Types in German. Annual Report of the Institute of Phonetics University of Copenhagen, [S. l.], v. 1, p. 85–86, 1967. DOI: 10.7146/aripuc.v1i.130581. Disponível em: https://tidsskrift.dk/ARIPUC/article/view/130581. Acesso em: 4 may. 2024.