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, 500 3 (2009) 1025 Published online: 29 April 2009 DOI: 10.1051/0004-6361/200809366e