An aluminium tool for multiple stellar generations in the globular clusters 47 Tucanae and M 4 E. Carretta, R. G. Gratton, A. Bragaglia, V. D’Orazi and S. Lucatello A&A, 550 (2013) A34 Published online: 22 January 2013 DOI: 10.1051/0004-6361/201220470