title: Multiple stable subharmonics for a periodic epidemic model.
abstract: The S leads to I leads to R epidemic model of K. Dietz with annual oscillation in the contact rate is shown to have multiple stable subharmonic solutions of different integral year periods.
mesh_terms: D004196:Disease Outbreaks / Q000453:epidemiology*; D006801:Humans; D008954:Models, Biological; D013223:Statistics as Topic; D013997:Time Factors