Abundance ratios of red giants in low-mass ultra-faint dwarf spheroidal galaxies P. François, L. Monaco, P. Bonifacio, C. Moni Bidin, D. Geisler and L. Sbordone A&A, 588 (2016) A7 Published online: 09 March 2016 DOI: 10.1051/0004-6361/201527181