1. A. M. Samoilenko and N. I. Ronto, Numerical-Analytic Methods for the Investigation of Solutions of Boundary-Value Problems [in Russian], Naukova Dumka, Kiev (1985).
2. A. A. Boichuk and A. M. Samoilenko, Generalized Inverse Operators and Fredholm Boundary-Value Problems, VSP, Utrecht (2004).
3. A. A. Boichuk, V. F. Zhuravlev, and S. M. Chuiko, “Periodic solutions of nonlinear autonomous systems in critical cases,” Ukr. Mat. Zh., 57, No. 9, 1180–1186 ((2005).
4. A. A. Boichuk, “Nonlinear boundary-value problems for systems of ordinary differential equations,” Ukr. Mat. Zh., 50, No. 2, 162–171 (1998).
5. Le Lyong Tai, “Numerical-analytic method for the investigation of autonomous systems of differential equations,” Ukr. Mat. Zh., 30, No. 3, 309–317 (1978).