Open clusters as key tracers of Galactic chemical evolution - III. Element abundances in Berkeley 20, Berkeley 29, Collinder 261, and Melotte 66P. Sestito, A. Bragaglia, S. Randich, R. Pallavicini, S. M. Andrievsky and S. A. KorotinA&A, 488 3 (2008) 943-958DOI: https://doi.org/10.1051/0004-6361:200809650
