1. Biological Delay Systems: Linear Stability Theory;MacDonals,1989
2. Dynamics of Controlled Mechanical Systems with Delayed Feedback;Hu,2002
3. Delay Differential Equations with Applications in Population Dynamics;Kuang,1993
4. Retarded Dynamical Systems: Stability and Characteristic Functions;Stépán,1989
5. History of delay equations;Hale,2006