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. 2021 Apr 1;404:126251. doi: 10.1016/j.amc.2021.126251

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Fig. 2 — Forward bifurcation diagram with respect to $R_{c}$ . All the fixed parameters are taken from Table 1 with $γ_{1} = 0.0001,$ $γ_{2} = 0.0001,$ $k_{2} = 0.0632,$ $σ_{1} = 0.2158,$ $σ_{2} = 0.03$ $σ_{4} = 0.4521$ and $0.2 < β < 0.35$ .