Khachatryan, A. Kh., and Kh. A. Khachatryan. 2009. “On Some Systems of Convolution-Type First-Order Integrodifferential Equations on the Semiaxis”.
Ukrains’kyi Matematychnyi Zhurnal 61 (9): 1277-92.
https://umj.imath.kiev.ua/index.php/umj/article/view/3099.