Suci Oktarini D. The Effect Of Using Duolingo To Improve Students’ Vocabulary Mastery At The Eleventh Grade Students Of SMAN 5 Pinggir. Jolly Journal of English Education [Internet]. 2023 Dec. 31 [cited 2026 May 27];1(2):162-76. Available from: https://ejournal.staihwduri.ac.id/index.php/jjee/article/view/61