Electronic Journal of Differential Equations,
Vol. 2012 (2012), No. 14, pp. 1-6.

Title: Positive periodic solutions for second-order neutral
       differential equations with functional delay

Author: Ernest Yankson (Univ. of Cape Coast, Ghana)

Abstract:
 We use Krasnoselskii's fixed point theorem   to
 prove the existence of positive periodic solutions of the
 second-order nonlinear neutral differential equation
 $$
 \frac{d^2}{dt^2}x(t)+p(t)\frac{d}{dt}x(t)+q(t)x(t)
 =c\frac{d}{dt}x(t-\tau(t))+f(t,h(x(t)),g(x(t-\tau(t)))).
 $$

Submitted November 1, 2011. Published January 20, 2012.
Math Subject Classifications: 34K20, 45J05, 45D05.
Key Words: Neutral equation; positive periodic solution.