Jiang, DaqingWei, JunjieZhang, Bo2020-08-172020-08-172002-07-30Jiang, D., Wei, J., Zhang, B. (2002). Positive periodic solutions of functional differential equations and population models. <i>Electronic Journal of Differential Equations, 2002</i>(71), pp. 1-13.1072-6691https://hdl.handle.net/10877/12404In this paper, we employ Krasnosel'skii's fixed point theorem for cones to study the existence of positive periodic solutions to a system of infinite delay equations, x'(t) = A(t)x(t) + ƒ(t, xt). We prove two general theorems and establish new periodicity conditions for several population growth models.Text13 pages1 file (.pdf)enAttribution 4.0 InternationalFunctional differential equationsPositive periodic solutionPopulation modelsArticle