Before revision:  Unlike the other equations such as the advection-diffusion equation, RFB method when applied to the Helmholtz equation  does not depend on another stabilized method to obtain approximations to the solutions of the sub-problems.
After revision:  Unlike the other equations such as the advection-diffusion equation, RFB method when applied to the Helmholtz equation , does not depend on another stabilized method to obtain approximations to the solutions of the sub-problems.