Zhanbusinova, B.Kh., B.K. Shaykhmetova, and A.K. Zhanbolova. 2015. “Operator Method of Solving Differential-Difference Equations of First Order”. Bulletin of the Karaganda University. Mathematics Series 79 (3):40-43. http://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/45.