221. http://www.2dfquasar.org/Papers/2002MNRAS.337..275C.pdf
... 337, 275292 (2002) The correlation of line strength with luminosity and redshift from composite quasi-stellar object spectra S. M. Croom,1 K. Rhook,1 E. A. Corbett,1 B. J. Boyle,1 H. Netzer,2 N. S. Loaring,3 L ... We measure highly significant Baldwin effects for most broad emission lines (C IV 1549, C III] 1909, Mg II 2798, H ,H ) and show that they are predominantly caused by correlations with luminosity, not redshift. ... The correlations of log W with log(1 + z ) for each line. ...