The knowledge of the velocity distribution was in a next step inserted into the fitting routine by allowing several rectangular Doppler boxes (representing monoenenergetic kinetic energies) to vary only in a limited range. It was found that a significant improvement needs at least an accuracy in the knowledge of the relative intensities of the Doppler distributions of 10%. In this case the error in the correlated fit above reduces from 2.4% to 1.7% for a statistics of 10000. The values for a statistics of 20000 decrease from 1.9% to 1.3%.