# Positive Periodic Solutions of Second-Order Differential Equations with Delays

##### Citations

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### Cites methods from "Positive Periodic Solutions of Seco..."

...In [3, 8, 9, 11, 12], the authors obtained the existence of positive periodic solutions for some first-order and second-order delay differential equations by using Krasnoselskii’s fixed-point theorem of cone mapping....

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1 citations

### Cites background from "Positive Periodic Solutions of Seco..."

...Recently, Li [8] discussed the existence of positive ω-periodic solutions of the second-order differential equation with delays of the form –u′′(t) + a(t)u(t) = f ( t, u(t – τ1), ....

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...The results obtained in [8] can deal with the case of second-order differential equations, but for high-order differential equations, for example,...

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...Lnu(t) = 1 2 u2(t – τ1) + 1 4 u2(t – τ2) + 1 8 u2(t – τ3), t ∈ R, the results of [8] are not valid....

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##### References

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