Napitupulu, Maya Farhan, Hazril Fikri Anwar, and Yani Lubis. “Error Pronouncing English Vowels”. Jurnal Pendidikan Rafflesia 1, no. 2 (June 30, 2023): 27–. Accessed June 1, 2026. https://jurnal.geinrafflesia.com/index.php/JPR/article/view/37.