ZavizionG. V. “Asymptotic Solution of a System of Integro-Differential Equations”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 12 (December 25, 1997): 1617–1623. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5166.