KhachatryanA. K., and KhachatryanK. A. “On the Construction of a Nonnegative Solution for One Class of Urysohn-Type Nonlinear Integral Equations on a Semiaxis”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 63, no. 1, Jan. 2011, pp. 110-8, https://umj.imath.kiev.ua/index.php/umj/article/view/2702.