1. Stability and Periodic Solutions of Ordinary and Functional Differential Equations;Burton,1985
2. Theory of Functional Differential Equations;Hale,1977
3. Asymptotic behavior of solutions of differential equations;Yashizaw,1987
4. Delay Differential Equations with Applications in Population Dynamics;Kuang,1993
5. Forced quasi periodic and almost periodic oscillations of nonlinear Duffing equations;Berger;Nonlinear Anal.,1992