Zulio Diva Ananta, Wanda Riani Hasibuan, and Yani Lubis. “The Students Challenges in Learning Difthong”. Jurnal Nakula : Pusat Ilmu Pendidikan, Bahasa dan Ilmu Sosial 3, no. 2 (January 14, 2025): 44–49. Accessed January 23, 2025. https://journal.aripi.or.id/index.php/Nakula/article/view/1603.