Boundedness of solutions for nonlinear differential equations

In this paper, the boundedness of all the solutions for quasilinear differential equation (ϕp(x′))′ + αϕp(x+) − βϕp(x−) + f(x) = e(t) is discussed, where ϕp(u) = {u}p−2u, p ≥ 2 is fixed, αβ are positive constants, f(χ) is semilinear at infinity and e(t) is a 2π-periodic function.