Setyaningsih, Kuntum Palupi, Agus Wijayanto, and Suparno Suparno. 2019. “English Vowels and Diphthongs Problems of Sundanese Learners”.
ELS Journal on Interdisciplinary Studies in Humanities
2 (4):571-81. https://doi.org/10.34050/els-jish.v2i4.8413.