Periodic solutions for a p-Laplacian-like NFDE system

We consider an n-dimensional p-Laplacian-like neutral functional differential equation (NFDE) in the formddtϕp[x′(t)−c(t)x′(t−τ)]+ddt∇F(x(t−τ))+β(t)∇G(x(t−δ(t)))=e(t),where c(t) and β(t) are sign-changeable.Using Mawhin's continuation theorem, we establish some criteria to guarantee the existence of periodic solutions for the above system, which generalize and improve on the corresponding results in related literature.