1. S. A. Chaplygin, A New Method of Approximate Integration of Differential Equations (Gostekhizdat, Moscow-Leningrad, 1950) [in Russian].
2. N. V. Azbelev, V. P. Maksimov, and L. F. Rakhmatullina, Introduction to Theory of Functional Differential Equations (Nauka, Moscow, 1991) [in Russian].
3. R. P. Agarwal, L. Berezansky, E. Braverman, and A. Domoshnitsky, Nonoscillation Theory of Functional Differential Equations with Applications (Springer, New York-Dordrecht-Heidelberg-London, 2012).
4. N. V. Azbelev and P.M. Simonov, Stability of Equation with Ordinary Derivatives(Perm Univ., Perm, 2001) [in Russian].
5. V. P. Maksimov and L. F. Rakhmatullina, “About a Presentation of a Solution to Linear Functional Differential Equation,” Differents. Uravneniya 9(6), 1026–1036 (1973).