Reza Artha Mevia, Ahmad Thoyyib Shofi and Lailatul Masruroh 2024. THE EFFECT OF USING DUOLINGO APPLICATION AS TEACHING MEDIA TO IMPROVE VOCABULARY MASTERY OF ELEVENTH GRADERS. J-Shelves of Indragiri (JSI). 6, 2 (Nov. 2024), 19–33. DOI:https://doi.org/10.61672/jsi.v6i2.2784.