WIDAYANTO, W.; SYAFII, A. Duolingo: An Alternative Application for Learning English Grammar and Vocabulary . Journal of English Language Teaching and Islamic Integration, [S. l.], v. 3, n. 01, p. 283–287, 2020. Disponível em: https://e-journal.hikmahuniversity.ac.id/index.php/jeltii/article/view/60. Acesso em: 24 apr. 2024.