1. I. T. Kiguradze and T. A. Chanturiya, Asymptotic Properties of Solutions to Nonautonomous Ordinary Differential Equations (Nauka, Moscow, 1990) [in Russian].
2. I. V. Astashova, J. Math. Sci. 126, 1361–1391 (2005) [Sovrem. Mat. Ee Prilozh. 8, 3–33 (2005)].
3. T. A. Chanturiya, Differ. Uravn. 28, 1009–1022 (1992).
4. V. A. Kozlov, Ark. Mat. 37, 305–322 (1999).
5. V. A. Kondrat’ev, Tr. Semin. im. I.G. Petrovskogo 16, 186–190 (1991).