Metallicity evolution, metallicity gradients, and gas fractions at z 3.4 P. Troncoso, R. Maiolino, V. Sommariva, G. Cresci, F. Mannucci, A. Marconi, M. Meneghetti, A. Grazian, A. Cimatti, A. Fontana et al. (2 more) A&A, 563 (2014) A58 Published online: 06 March 2014 DOI: 10.1051/0004-6361/201322099