Solar abundances (Asplund et al. 2009; Scott et al. 2015b,a; Grevesse et al. 2015, thick black line) compared with the determined photospheric abundances of G191−B2B (blue circles, Rauch et al. 2013, and this work) and RE 0503−289 (red squares, Dreizler & Werner 1996; Rauch et al. 2012, 2014a,b, 2015b, 2016b,a, 2017a,b, and this work). The uncertainties of the abundances are about 0.2 dex in general. Arrows indicate upper limits. Top panel: abundances given as logarithmic mass fractions. Determined TIE abundances of subsequent species are combined with lines. Bottom panel: abundance ratios to respective solar values, [X] denotes log (fraction / solar fraction) of species X. The dashed green line indicates solar abundances.