Existence of periodic solutions for a fourth-order -Laplacian equation with a deviating argument

In this paper, we study the existence of periodic solutions for a fourth-order p -Laplacian differential equation with a deviating argument as follows: [ φ p ( u ″ ( t ) ) ] ″ + f ( u ″ ( t ) ) + g ( u ( t − τ ( t ) ) ) = e ( t ) . Under various assumptions, the existence of periodic solutions of the problem is obtained by applying Mawhin’s continuation theorem.