NLTE determination of the sodium abundance in a homogeneous sample of extremely metal-poor starsS. M. Andrievsky, M. Spite, S. A. Korotin, F. Spite, P. Bonifacio, R. Cayrel, V. Hill and P. FrançoisA&A, 464 3 (2007) 1081-1087DOI: https://doi.org/10.1051/0004-6361:20066232
