Asplund, M. Stellar Astrophysics, MPI for Astrophysics, Max Planck Society;
Norris, J. E., Bessell, M. S., Yong, D., Christlieb, N., Barklem, P. S., Asplund, M., et al. (2013). The most metal-poor stars - I. Discovery, data, and atmospheric parameters. The Astrophysical Journal, 762(1): 25, pp. 1-16. doi:10.1088/0004-637X/762/1/25.