Measured lithium abundances for targets on the main sequence/sub-giant branch as a function of the effective temperature (upper panel) and the sodium content (lower panel, stars at T_eff  >  5880 K only). The primordial lithium level implied by WMAP measures plus SBBN theory (shaded area) is also marked for reference. In the lower panel, filled squares indicate the mean Li content for the Na-rich/Na-poor sub-samples. The continuous line is a least square fit to the individual data. In both panels, the big open star marks the position of star # 37934.