1. Introduction to Functional Differential Equations;Hale,1993
2. Delay Differential Equations with Applications in Population Dynamics;Kuang,1993
3. Retarded Dynamical Systems: Stability and Characteristic Functions;Stépán,1989
4. An Introduction to Difference Equations;Elaydi,1999
5. Global Behavior of Nonlinear Difference Equations of Higher Order with Applications;Kocić,1993