Salim AL-Kutubi , H., and I. Razzaq AL-Saiq. “On Student Comprehension For There Year Courses In Mathematics Department”. University of Thi-Qar Journal of Science, Vol. 1, no. 3, May 2019, pp. 64-103, https://www.jsci.utq.edu.iq/index.php/main/article/view/187.