In ref. [I] , numerical experiment reveals scaled superstructures In the bifurcation diagram for the damped nonlinear drift-wave driven by a traveling wave. In this paper, it is shown that the resonance between the solution of driv en-damped equation and that of the unperturbed system is the cause of winding number bifurcation and hence of the superstructure. The scaling law for the wavenumbers and frequencies calculated accordingly is in agreement with the numerical results.