1LIU Wei-min,LEVIN S A,IWASA Y,et al.Influence of nonlinear incidence rates upon the behavior of SIRS epidemiological models[J].J Math Biol,1986,23(1):187-204.
2LIU Xuan-liang.Qualitative analysis of SIRS epidemiological models with nonlinear incidence rates[J].J Biomath,1996,11(2):1-6.
3GOBBER F,WILLAMOWSKI K D.Liapunov approach to multiple Hopf bifurcation[J].J of Math Anal and Appl,1979,71(3):333-350.
