1. S. V. Coffman and J. J. Schäffer, ?Dichotomies for linear difference equations,? Math. Ann.,172, 139?166 (1967).
2. Yu. L. Daletskii and M. G. Krein, Stability of Solutions of Differential Equations in Banach Space, Amer. Math. Soc. (1974).
3. M. A. Krasnosel'skii, V. Sh. Burd, and Yu. S. Kolesov, Nonlinear Almost-Periodic Oscillations [in Russian], Nauka, Moscow (1970).
4. J. L. Massera and J. J. Schaffer, Linear Differential Equations and Function Spaces, Academic Press (1966).
5. P. Hartman, Ordinary Differential Equations, Wiley, New York (1964).