Boundedness of solutions for reversible systems

In this paper, we study the boundedness of all the solutions for the following second order nonlinear differential equation(?p(x'))'+f(x)?p(x')+g(x)=e(t)'=ddtwhere ?p(u)=|u|p-2u, p>1, f,g?C∞ (R?{0}) and odd, e?C∞(R/Z) is odd, g is subquasilinear: sgn(x)?g(x)?+∞, g(x)/?p(x)?0 as |x|?∞.