D. S. Amaniarsih, N. Asrul, J. Juliana, dan E. Ginting, “THE EFFECTIVENESS OF USING THE DUOLINGGO APPLICATION IN IMPROVING STUDENTS’ MOTIVATION AND ENGLISH-SPEAKING SKILL AT UNIVERSITAS POTENSI UTAMA MEDAN”, J. Pedagogi, vol. 11, no. 1, hlm. 46–54, Jan 2025.