Distances and ages of NGC 6397, NGC 6752 and 47 Tuc R. G. Gratton, A. Bragaglia, E. Carretta, G. Clementini, S. Desidera, F. Grundahl and S. Lucatello A&A, 408 2 (2003) 529-543 Published online: 17 November 2003 DOI: 10.1051/0004-6361:20031003