Research Article

Positive Periodic Solutions of an Epidemic Model with Seasonality

Figure 4

Phase plane of and . (a) When the parameter values are , , and , , , , and . (b) When the parameter values are , , , and , , , , and . The value of other parameters can be seen in Table 1.
470646.fig.004a
(a)
470646.fig.004b
(b)