AGB stars as tracers of metallicity and mean age across M 33 M.-R. L. Cioni, M. Irwin, A. M. N. Ferguson, A. McConnachie, B. C. Conn, A. Huxor, R. Ibata, G. Lewis and N. Tanvir A&A, 487 1 (2008) 131-146 Published online: 22 May 2008 DOI: 10.1051/0004-6361:200809366