  We are conducting a high-resolution follow-up of candidate EMP stars
extracted from the Sloan Digital Sky Survey (SDSS; York et al. 2000) using UVES
at the VLT. Three of the programme stars, SDSS J0912+0216, SDSS J1036+1212 and
SDSS J1349-0229, where deliberately targetted as CEMP stars since a strong $G$
band was evident from the SDSS spectra and the weakness of the Ca {\sc ii} K
line testified their very low metallicity. The UVES high resolution follow-up
confirmed the original findings ([Fe/H] $<-2.50$) and allowed a more detailed
investigation of their chemical composition. We determined the carbon abundance
from molecular lines which form in the outer layers of the stellar atmosphere.
It is known that convection in metal-poor stars induces very low temperatures
which are not predicted by classical 1D stellar atmospheres. To obtain the
correct temperature structure, one needs full 3D hydrodynamical models. 3D
carbon abundances were determined for all three stars, using CO$^5$BOLD 3D
hydrodynamical model atmospheres. 3D effects on the carbon abundance are found
to be quite significant for these stars, with 3D corrections of up to --0.7
dex. Two of the stars, SDSS J0912+0216 and SDSS J1349-0229 exhibit an
overabundance of neutron capture elements which classifies them as CEMP-s. Star
SDSS J1036+1212, instead belongs to the elusive class of CEMP-no/s stars, with
enhanced Ba, but deficient Sr, of which it is the third member discovered to
date.
