Nadeak, Bernadetha, and Lamhot Naibaho. 2020. “THE EFFECTIVENESS OF MASTERY LEARNING TECHNIQUE ON IMPROVING STUDENTS’ ABILITY IN COMPLETING ENGLISH NATIONAL EXAMINATION”. International Journal of Research -GRANTHAALAYAH 8 (2):57-62. https://doi.org/10.29121/granthaalayah.v8.i2.2020.184.