Subtracting the circular motion (i.e., B₁ coefficient) from the data, we end up with the velocity residual maps, characterized by mean residuals close to zero and an rms smaller than 20 km s^-1 for the whole sample. If we assume that the four objects have almost the same rms, this plot clearly implies higher circular velocities for the class 0 galaxies, while we note that a lower B₁ term is derived for the class 2 ones. Their rotation is clearly shown in Figs. 5 − 8.