Upper panel: comparison of the evolution of [Zn/Fe] with [Fe/H] in the stellar population predicted by a chemical evolution model for a classical bulge with star formation rate normalization ν_SF = 3 Gyr^-1 and total mass of 1.5 × 10¹⁰M_⊙, with the [Zn/Fe] vs. [Fe/H] data for the present sample, for the DLA samples by Cooke et al. (2013), Akerman et al. (2005) and Vladilo et al. (2011), and for the halo stars from Cayrel et al. (2004). The Fe abundances of Akerman et al. (2005) and Vladilo et al. (2011) have been corrected for dust depletion. (No dust correction was needed for the Cooke et al. sample, because their systems have [Fe/H] < −2.) Lower panel: the same as the upper model, but using, at low metallicities, the yields of Woosley & Weaver (1995) instead of those of hypernovae.