Sardaryan, T. G., T. E. Terjyan, and K. A. Khachatryan. “Sardaryan T. G. On the Solvability of One System of nonlinear Hammerstein-Type Integral Equations on the Semiaxis”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 69, no. 8, Aug. 2017, pp. 1107-22, http://umj.imath.kiev.ua/index.php/umj/article/view/1762.