Plot of our data (solid diamonds) on the L − Z plane. Open squares represent the galaxies in the redshift range 0.47 < z < 0.92 from the Canada-France Redshift Survey (Lilly et al. 2003), open triangles mark the galaxies with 0.3 < z < 0.6 from the GOODS-North Field (Kobulnicky & Kewley 2004), and open circles refer to the local galaxies of the Nearby Field Galaxy Sample (Jansen et al. 2000). The solid line indicates the L − Z relation obtained by Tremonti et al. (2004) for local galaxies. The magenta dashed line represents the linear fit (12 + log (O/H)= aM_B + b) through our data points except for J154925.24-003717.8 and J003806.59+000421.9.