Ningsih, Shabrina, and Ade Romadhony. “Difficulty Level Identification of Indonesian and Mathematics Multiple Choice Questions Using Machine Learning Approach”. Building of Informatics, Technology and Science (BITS) 5, no. 1 (June 29, 2023): 236−245. Accessed May 16, 2026. https://ejurnal.seminar-id.com/index.php/bits/article/view/3649.