Ratios of alpha elemements to iron for our programme stars (filled circles) compared to those of the stars of Bonifacio et al. (2009) (open circles). The spectra of SDSS J004029+160416 and SDSS J002113-005005 observed in periods 78 and 81 were treated independently and the points referring to the derived abundances are connected by a line. The one referring to the two measures of SDSS J004029+160416 is not visible, since the two points are indistinguishable at the resolution of the plot.