4Thieme H R, Castillo-Chavez C. On the role of variable infectivity in the dynamics of the Human Immunodeficiency virus epidemic [ A]. Castillo-Chavez C.Mathematical and Statistical Approaches to AIDS Epidemiology [C]. New York: Springer, 1989.
5Anderson R M. Transmission dynamics and control of infectious diseases [A]. Anderson R M, May M R.Population Biology of Infectious Diseases, Life Sciences Research Report 25 [C]. Berlin: Springer,1982.
6Heesterbeek J A P, Metz J A J. The saturating contact rate in marriage and epidemic models [J]. J Math Biol, 1993, 31:529-539.
7Hale J K. Ordinary differential equations [M]. New York: Wiley-Interscience, 1969.
8Hofbauer J, So J W H. Uniform persistence and repellors for maps [J]. Proc Amer Math Soc, 1989,107:1137-1142.
9Muldowney J S. Compound matrices and ordinary differential equations [J]. Rocky Mount J Math, 1990,20 : 857-872.
10Esteva L, Vargas C. Analysis of a dengue disease transmission model [J]. Math Biosci, 1998, 150:131-151.
