Periodic solutions for a p-Laplacian-like NFDE system

We consider an n-dimensional p-Laplacian-like neutral functional differential equation (NFDE) in the form d d t ϕ p [ x ′ ( t ) − c ( t ) x ′ ( t − τ ) ] + d d t ∇ F ( x ( t − τ ) ) + β ( t ) ∇ G ( x ( t − δ ( t ) ) ) = e ( t ) , where c(t) and β ( t ) are sign-changeable. Mawhinʹs 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.