Abdeen, F., & Albiladi, W. (2021). Gamification and technology-based learning: Uncovering the potential of using games in language teaching and learning. Journal of Studies in Education, 11(2), 62. https://doi.org/10.5296/jse.v11i2.18339
Ary, D., Jacobs, L. C., Sorensen, C. K., & Walker, D. (2019). Introduction to research in education (10th ed.). Cengage.
Astarilla, L. (2018). University Students’ Perception Towards the Use of Duolingo Application in Learning English. In CelSciTech-UMRI 2018 Conference Proceedings (Vol. 3, Sep. 2018). STMIK-AMIK Riau, Pekanbaru, Riau, Indonesia.
Bader, M., Cloarec, M., Goumy, M., & Hussein, D. (2022). The advantages and limits of gamification mechanisms: A Duolingo case study. Retrieved from https://comtechp7.hypotheses.org/files/2022/09/The-Advantages-and-Limits-of-Gamification-Mechanisms-A-Duolingo-Case-Study.pdf
Boudadi, N. A., & Gutiérrez-Colón, M. (2020). Effect of gamification on students’ motivation and learning achievement in Second Language Acquisition within higher education: A literature review 2011-2019. The EUROCALL Review, 28(1), 57.
Buenaño, C., Trujillo, E., Pazmiño, S., & Carvajal, S. (2023). Fostering English vocabulary learning through gamification strategy: A preliminary study. Concienciadigital, 6(1.4), 60-78 .
Burston, J. (2013). Mobile assisted language learning: A review of the research. Computer Assisted Language Learning, 26(4), 303–321.
Burston, J. (2013). Mobile assisted language learning: A review of the research. Computer Assisted Language Learning, 26(4), 303–321.
Burston, J. (2015). Mobile assisted language learning: Concepts, research, and practice. Routledge.
Chen, G., Wang, F., & Li, X. (2020). Mobile assisted language learning: A systematic review of research from 2008 to 2018. Computer Assisted Language Learning, 33(3), 219-242.
Devendren, A., & Nasri, N. B. M. (n.d.). Systematic Review: Students’ Perceptions of the Use of Gamification. International Journal of Academic Research in Business and Social Sciences, 12(8), 14268. https://doi.org/10.6007/ijarbss/v12-i8/14268
Dornyei, Z. (2007). Research methods in applied linguistics. Oxford University Press.
Faradisa, L., Afrila, I., Faroh, I., & Choirunnisa, G. (2022). The use of Duolingo to assist EFL students of Prof. KH. Saifuddin Zuhri State Islamic University in learning vocabulary. Conference on English Language Teaching, 2, 14-25. https://doi.org/10.24090/celti.v2.29
Gimeno-Sanz, A., Martinez-Fernandez, M., & Hernandez-Castro, J. L. (2020). Towards a new educational paradigm: Mobile-assisted language learning in higher education. Computer Assisted Language Learning, 33(2), 165-186.
Hamari, J., Koivisto, J., & Sarsa, H. (2014). Does gamification work? A literature review of empirical studies on gamification. https://doi.org/10.1109/hicss.2014.377
Hassan, M., Emam, H., & Sayed, F. (2023). Using gamification to enhance sixth grade pupils’ motivation. Scientific Journal of the Faculty of Education, University of Wadi El-Gedid, 15(44), 226-239. https://doi.org/10.21608/sjsw.2023.288031
Hassan, M., Habiba, U., Majeed, F., & Shoaib, M. (2019). Adaptive gamification in e-learning based on students’ learning styles. Interactive Learning Environments. https://doi.org/10.1080/10494820.2019.1588745
Ho, J. (2019). Discursive representations of domestic helpers in cyberspace. Discourse Studies, 22(1), 48–63. https://doi.org/10.1177/1461445619887539
Huynh, D., Zuo, L., & Iida, H. (2018). An Assessment of Game Elements in Language-Learning Platform Duolingo. 2018 4th International Conference on Computer and Information Sciences (ICCOINS), 1-4. https://doi.org/10.1109/ICCOINS.2018.8510568.
Irwit Santi, L., Hilal, A., & Rismiyanto (2023). Review of Duolingo Application in Learning English. Channing: Journal of English Language Education and Literature.
Jiang, X., Rollinson, J., Plonsky, L., Gustafson, E., & Pająk, B. (2021). Evaluating the reading and listening outcomes of beginning‐level Duolingo courses. Foreign Language Annals, 54(4), 974-1002. https://doi.org/10.1111/flan.12600
Kazu, I. Y., & Kuvvetli, M. (2022). Improve speaking skills with Duolingo’s mobile game-based language learning. Asian Journal of Education and Training, 10(1). https://doi.org/10.20448/edu.v10i1.5488
Khaled, A. E. (2021). The impact of using gamification on developing English language speaking skills among preparatory school students. Journal of Scientific Research in Education, 22(1), 388-405. https://doi.org/10.21608/jsre.2021.54341.1236
Kukulska-Hulme, A., & Viberg, O. (2018). Mobile learning: Transforming education. Routledge.
Loewen, S., Crowther, D., Isbell, D., Kim, K., Maloney, J., Miller, Z., & Rawal, H. (2019). Mobile-assisted language learning: A Duolingo case study. ReCALL, 31, 293 - 311. https://doi.org/10.1017/S0958344019000065.
Loewen, S., Smith, P., & Jones, R. (2020). Duolingo as a mobile assisted language learning tool: A mixed-methods study of Turkish language learners. Computer Assisted Language Learning, 33(4), 317-338.
Loewen, S., Smith, P., & Jones, R. (2020). Duolingo as a mobile assisted language learning tool: A mixed-methods study of Turkish language learners. Computer Assisted Language Learning, 33(4), 317-338 .
Mila, H., & Mahbub, M. (2022). An alternative board game to promote EFL learners’ grammatical skill. Enjourme (English Journal of Merdeka), 7(1), 78-87. https://doi.org/10.26905/enjourme.v7i1.7043
Mogavi, R., Guo, B., Zhang, Y., Haq, E., Hui, P., & Ma, X. (2022). When Gamification Spoils Your Learning: A Qualitative Case Study of Gamification Misuse in a Language-Learning App. Proceedings of the Ninth ACM Conference on Learning @ Scale. https://doi.org/10.1145/3491140.3528274.
Nurhisyam, R., Usman, S., Agussatriana, A., & Rofiqoh, R. (n.d.). University students’ perception in learning vocabulary through Duolingo. e-Journal of ELTS. https://doi.org/10.22487/elts.v10i3.3189
Nyazi, A. K. (2023). Students’ Perceptions of a Gamification in Higher Education. Journal of Educational and Psychological Sciences, 3(8), 23. https://doi.org/10.26389/ajsrp.y030823
Pham, A. T. V., & Nguyen, L. D. (2021). Students’ Perceptions of Gamification: A Case Study in Business Courses at an Institution of Higher Education. In _2021 3rd International Conference on Modern Educational Technology (pp. 1-6). Association for Computing Machinery. https://doi.org/10.1145/3468978.3468998
Phuong, T. (2020). Gamified learning: Are Vietnamese EFL learners ready yet? International Journal of Emerging Technologies in Learning (IJET), 15(24), 242. https://doi.org/10.3991/ijet.v15i24.16667
Rassaei, M. (2020). The use of mobile applications in language learning: A review of the literature. Computer Assisted Language Learning, 33(1), 5-26.
Richards, J. (2015). The changing face of language learning: Learning beyond the classroom. RELC Journal, 46(1), 5-22. https://doi.org/10.1177/0033688214561621
Ritonga, M., Febriani, S., Kustati, M., Khaef, E., Ritonga, A., & Yasmar, R. (2022). Duolingo: An Arabic speaking skills’ learning platform for andragogy education. Education Research International, 1-9. https://doi.org/10.1155/2022/7090752
Sato, M., Watanabe, Y., & Shibata, T. (2020). Mobile assisted language learning in Japan: A survey of current trends and challenges. Computer Assisted Language Learning, 33(5), 403-421.
Seaborn, K., & Fels, D. I. (2015). Gamification in theory and action: A survey. International Journal of human-computer studies, 74, 14-31. https://doi.org/10.1016/j.ijhcs.2014.09.006
Shortt, M., Tilak, S., Kuznetcova, I., Martens, B., & Akinkuolie, B. (2021). Gamification in mobile-assisted language learning: a systematic review of Duolingo literature from public release of 2012 to early 2020. Computer Assisted Language Learning, 36(3), 517–554. https://doi.org/10.1080/09588221.2021.1933540
Sukarya, D., Kamil, A., & Utami, P. (2022). The students’ experiences in implementing Duolingo-assisted listening learning. Jiip - Jurnal Ilmiah Ilmu Pendidikan, 5(10), 3941-3946. https://doi.org/10.54371/jiip.v5i10.972
Syafrizal, S., Cahyaningrum, N., & Syamsun, T. R. (2022). Duo Lingo application for teaching speaking skills class: Students’ perception of speech ability. International Database Engineering and Applications Symposium. https://doi.org/10.24256/ideas.v10i1.2881
Torres-Gastelú, C. A., Olguin-Barrera, A., & Angulo-Armenta, J. (2022). Perception of young university students on the acceptance of gamification in the learning process. In _2022 XII International Conference on Virtual Campus (JICV) (pp. 1-6). IEEE. https://doi.org/10.1109/JICV56113.2022.9934320
Wiyati, R., & Amelia, S. (2022). STUDENTS’ REFLECTION TOWARD LEARNING VOCABULARY USING DUOLINGO APPLICATION. JELA (Journal of English Language Teaching, Literature and Applied Linguistics), 4(1), 75-90. https://doi.org/10.37742/jela.v4i1.75
Yana, D. (2021). Applying Duolingo as English Learning Media: How do Students Perceive it? INTERNATIONAL JOURNAL OF LANGUAGE PEDAGOGY.
Zeng, C., & Fisher, L. (2023). Opening the “black box”: How out-of-class use of Duolingo impacts Chinese junior high school students’ intrinsic motivation for English. ECNU Review of Education, 7(2), 283-307. https://doi.org/10.1177/20965311231171606
Zhang, S., & Hasim, Z. (2023). Gamification in EFL/ESL instruction: A systematic review of empirical research. Frontiers in Psychology, 13. https://doi.org/10.3389/fpsyg.2022.1030790.