Existence of periodic solutions for a p-Laplacian neutral functional differential equation

In this paper, we study the existence of periodic solutions for a p-Laplacian neutral functional differential equation, as follows (φp(x′(t)−c(t)x′(t−r)))′=f(x(t))x′(t)+β(t)g(x(t−τ(t)))+e(t). It is meaningful that c(t) is not a constant function, and that the functions c(t) and β(t) are allowed to change signs, which are different from the corresponding ones of known literature.