1. Bainov, D. D., and Simeonov, P. S. (1989).Systems with Impulse Effect: Stability, Theory and Applications, Ellis Horwood Limited.
2. Dannan, F. M., and Elaydi, S. (1986).Journal of Mathematical Analysis and Applications,113, 562?577.
3. Lakshmikantham, V., Bainov, D. D., and Simeonov, P. S. (1989).Theory of Impulsive Differential Equations, World Scientific, Singapore.
4. Samoilenko, A. M., and Perestyuk, N. A. (1987).Differential Equations with Impulse Effect, Vi??a ?kola, Kiev (in Russian).