Figure 9: Effective radius (a) and effective surface brightness (b) of bulges of S0 (red points), early-type (crosses), and late-type (squares) spirals as a function of the bulge absolute magnitude. The dashed line in the left panel corresponds to the relation followed by ellipticals galaxies from the Coma cluster. The continuous lines in the left panel correspond to the mean values of the data points in one- magnitude bins: S0s (red line) and Sa-Sbc (blue line). Credit: Laurikainen et al. [21]. Reproduced by permision from WILEY.