Sulfur abundances in three Galactic clusters: Ruprecht 106, Trumpler 5, and Trumpler 20 F. Lucertini, L. Monaco, E. Caffau, A. Mucciarelli, S. Villanova, P. Bonifacio and L. Sbordone A&A, 671 (2023) A137 Published online: 17 March 2023 DOI: 10.1051/0004-6361/202244646