Black hole mass computed from the fiducial relation of Vestergaard & Peterson (2006) based on FWHM Hβ vs. the ones computed from the C IVλ1549 FWHM following Park et al. (2013), for Pop. A (blue) and B (red) HE sources. Values of M_BH obtained from the Vestergaard & Peterson (2006) C IVλ1549 scaling law after the correction suggested by Brotherton et al. (2015, small dots) are shown by small open circles. Lower panel: residuals as a function of M_BH. The average and the scatter reported for Populations A and B refer to the Park et al. (2013) scaling laws.