1. Systems with Impulse Effect, Theory and Applications;Bainov,1989
2. Periodic time-dependent predator–prey system;Cushing;SIAM J. Appl. Math.,1977
3. Coincidence Degree and Nonlinear Differential Equations;Gaines,1977
4. On the delay differential equations with impulses;Gopasymy;J. Math. Anal. Appl.,1989
5. Delay Differential Equations with Applications in Population Dynamics;Kuang,1993