Setyaningsih KP, Wijayanto A, Suparno S. English Vowels and Diphthongs Problems of Sundanese Learners. ELS-JISH [Internet]. 2019 Dec. 17 [cited 2025 Mar. 31];2(4):571-8. Available from: http://journal.unhas.ac.id/index.php/jish/article/view/8413