Setyaningsih, Kuntum Palupi, Agus Wijayanto, and Suparno Suparno. “English Vowels and Diphthongs Problems of Sundanese Learners”. ELS Journal on Interdisciplinary Studies in Humanities 2, no. 4 (December 17, 2019): 571-581. Accessed November 22, 2024. https://journal-old.unhas.ac.id/index.php/jish/article/view/8413.