FRØKJÆR-JENSEN, Børge. Comparisons between the Vowel Formant Frequencies in Speech and Song. ARIPUC, [S. l.], v. 3, p. 115–127, 1969. DOI: 10.7146/aripuc.v3i.130757. Disponível em: https://tidsskrift.dk/ARIPUC/article/view/130757. Acesso em: 5 dec. 2025.