Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts I. Minchev, B. Famaey, A. C. Quillen, P. Di Matteo, F. Combes, M. Vlajić, P. Erwin and J. Bland-Hawthorn A&A, 548 (2012) A126 Published online: 05 December 2012 DOI: 10.1051/0004-6361/201219198