ZavizionG. V. “Asymptotic Solutions of Systems of Linear Degenerate Integro-Differential Equations”. Ukrains’kyi Matematychnyi Zhurnal 55, no. 4 (April 25, 2003): 435-445. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3917.