Comparison of the observed abundances of AS0039 (NLTE) to theoretical predictions for pure descendants of Pop III stars, varying their SN explosion energy, mixed fraction, and initial mass. In the upper panel, we fixed the initial mass to 20 M_⊙, and, in the lower panel, we fixed the mixed fraction to f_mix = 0.063. Best fits are magenta, while the worst fits, with χ² ≥ 5 (i.e. ≥5 times the minimum), are shown with a red colour.