Zega, Yudika Syukurniati, Hidayati Daeli, Adieli Laoli, and Trisman Harefa. 2026. “Improving the Students’ Vocabulary by Using Duolingo at Seventh Grade of SMP Negeri 2 Gunungsitoli Utara”. RIGGS: Journal of Artificial Intelligence and Digital Business 5 (1):2331-39. https://doi.org/10.31004/riggs.v5i1.6470.