Iskandarov, S., and G. T. Khalilova. “THE Lower Estimations of Solutions of Linear VOLTERRA Integral-Differential Equation of Fourth Order”. Journal of Mathematics, Mechanics and Computer Science 76, no. 1 (March 23, 2013): 43–52. Accessed July 3, 2024. https://bm.kaznu.kz/index.php/kaznu/article/view/86.