Extreme gas properties in the most distant quasars R. Maiolino, E. Oliva, F. Ghinassi, M. Pedani, F. Mannucci, R. Mujica and Y. Juarez A&A, 420 3 (2004) 889-897 Published online: 04 June 2004 DOI: 10.1051/0004-6361:20035704