Comparison between the metallicities from the literature and those obtained in this work. Top left panel: VF05; top right panel: NO04; bottom panel: TA05. Dashed lines represent the best linear fit (y = m ∗ x + b) between our metallicities and those given in the corresponding works. The coefficients are: m = 1.18 ± 0.05, b =  −0.008 ± 0.008 for VF05; m = 1.04 ± 0.05, b = 0.064 ± 0.013 for N04; and m = 0.99 ± 0.05, b =  −0.017 ± 0.011 for TA05.