[1] BAUER F., WONG J. S. W.: On asymptotic behavior of perturbed linear systems. J. Diff. Equat., 6, 142-153. MR 0239213

[2] CESARI L.: Asymptotic behavior and stability problems in ordinary differential equations. Springer-Verlag, Berlin-Göttingen-Heidelberg, 1959. MR 0118904 | Zbl 0082.07602

[3] ELŠGOLC, LE. E., NORKIN S. B.: Vedenie v teoriju differenciaľnych uravnenij s otklonjajuščímsja argumentom. „Nauka" 1971, Moskva.

[4] FUTÁK J.: On existence and asymptotic behavior of solutions of nonlinear delay differential system. Archiv. Math., 1, 1978, Brno.

[5] HALLAM T. G., HEIDEL J. W.: The asymptotic manifolds of a perturbed linear system of differential equations. Trans. Amer. Math. Soc. 149, 1970, 233-241. MR 0257486 | Zbl 0186.41502

[6] HOSAM EL-DIN: On the asymptotic properties of solutions of nonlinear systems. Arch. Math., 4, 1976, 179-190. MR 0473366 | Zbl 0353.34049

[7] KATO J.: The asymptotic equivalence of systems of functional differential equations. J. Diff. Equat. 1, 1965, 306-332. MR 0177221 | Zbl 0151.10202

[8] ŠVEC M.: Asymptotic relationship between solutions of two systems of differential equations. Czechosl. Math. J., 24 (99) 1974, 44-58. MR 0348202 | Zbl 0322.34037

[9] ŠVEC M.: Some properties of functional differential equations. Bolletino U.M.I., (4) 11, Suppl. fasc. 3, 1975, 467-477. MR 0430476

[10] TRENCH W. F.: Asymptotic behavior of solutions of $Lu = g(t, u, ..., u^{(k-1)}). J. Diff. Equat. 11, 1972, 38-48. MR 0293195