Liapunov transformations of nonlinear periodic differential eqautions

It's a well known fact that linear differential equations are reducible to linear autonomous deffintial equation with a constant matrix (Floquet-Liapunov theorem). We consider nonlinear periodic differential equation and construct the example of nonreducible differential equation to autonomous equation in the special Liapunov group of nonlinear transformations containing linear Liapunov transformations.