Observed and synthetic spectra around the La lines at 6262 Å and 6390 Å for the s-poor star III-14 observed at LICK (left panels), and the s-rich star III-52 observed with UVES (right panels). In each panel the points represent the observed spectrum. The magenta line is the spectrum computed with no contribution from La ii; the black line is the best-fitting synthesis (with the La abundance given in Table 6); and the red and blue lines are the syntheses computed with La abundances altered by  ± 0.2 dex from the best value.