Kaku Zakka, et al. “Development and Preliminary Validation of Difficulty Index, Discrimination and Distractor of Measurement and Evaluation Proficiency Test for Undergraduate Students”. African Journal of Education,Science and Technology (AJEST), vol. 8, no. 4, Sept. 2026, pp. 228-42, https://ajest.org/index.php/ajest/article/view/1036.