1 Ahmad S, Mohana Rao M R. Asymptotically periodic solutions of n-competing species problem with time
delay. J Math Anal Appl, 1994, 186: 557-571
2 Freedman H I, Ruan S. Uniform persistence in functional differential equations. J Differential Equations,
1995, 115: 173-192
3 Kuang Y, Smith H L. Global stability for infinite delay Lotka-Volterra type systems. J Differential Equa-
tions, 1993, 103: 221-246
4 Kuang Y, Tang B. Uniform persistence in nonautonomous delay differential Kolmogorov type population
models. Rocky Mountain J Math, 1994, 24: 165-186
5 Kuang Y. Global stability in delay differential systems without dominating instantaneous negative feed-
backs. J Differential Equations, 1995, 119: 503-532
6 Kuang Y. Global stability in delayed nonautonomous Lotka-Volterra type systems without saturated equi-
libria. Differential Integral Equations, 1996, 9: 557-567
7 Tang B, Kuang Y. Permanence in Kolmogorov type systems of nonautonomous functional differential
equations. J Math Anal Appl, 1996, 197: 427-447
8 Wang W, Chen L, Lu Z. Global stability of a competition model with periodic coefficients and time delays.
Canadian Appl Math Quarterly, 1995, 3: 365-378
9 Wang L, Zhang Y. Global stability of Volterra-Lotka systems with delay. Differential Equations Dynam
Sys, 1995, 3: 205-216
10 Bereketoglu H, Gyori I. Global asymptotic stability in a nonautonomous Lotka-Volterra type systems with
infinite delay. J Math Anal Appl, 1997, 210: 279-291
11 Teng Z, Yu Y. Some new results of nonautonomous Lotka-Volterra Competitive systems with delays. J
Math Anal Appl, 2000, 241: 254-275

12 Gopalsamy K. Stability and Oscillations in Delay Differential Equations of Population Dynamics. Dor-
drecht, Norwell, MA: Kluwer Academic, 1992. 292-370
13 Kuang Y. Delay Differential Equations with Applications in Population Dynamics. Boston: Academic
Press, 1993. 119-309
14 Hale J. Theory of Functional Differential Equations. Heidelberg: Springer-Verlag, 1977. 36-56