[Ca/Fe] and [Mg/Fe] ratios as a function of [Fe/H] from the analysis of our SDSS/SEGUE and BOSS samples. The reliable estimates after applying the upper limit evaluation are indicated as black dots. Red arrows show the cases where only an upper limit for the abundances could be obtained, and the direction the ratio would be situated in this diagram. The two stars for which we obtain high [Ca/Fe] and [Mg/Fe] are shown as green dots.