BALAS, Anna. English Centering Diphthong Production by Polish Learners of English . Research in Language, Poland, v. 7, p. 129–148, 2009. DOI: 10.2478/v10015-009-0009-2. Disponível em: https://www.czasopisma.uni.lodz.pl/research/article/view/8193. Acesso em: 7 aug. 2026.