Induced gravitational collapse at extreme cosmological distances: the case of GRB 090423 R. Ruffini, L. Izzo, M. Muccino, G. B. Pisani, J. A. Rueda, Y. Wang, C. Barbarino, C. L. Bianco, M. Enderli and M. Kovacevic A&A, 569 (2014) A39 Published online: 16 September 2014 DOI: 10.1051/0004-6361/201423457