Baryonic Density from Primordial Li
  Lithium abundances in a selected sample of halo stars have been revised by using new accurate Teff. From 41 plateau stars we found no evidence for intrinsic dispersion, a tiny trend with Teff and no trend with [Fe/H]. These results argue against depletion by either stellar winds, diffusion or rotational mixing. Therefore the Li observed in PopII stars provides a reliable estimate of the baryonic density. A more detailed discussion can be found in Bonifacio & Molaro (1996). 
Piercarlo Bonifacio and Paolo Molaro