The Gaia-ESO Survey: No sign of multiple stellar populations in open clusters from their sodium and oxygen abundances
A. Bragaglia, V. D’Orazi, L. Magrini, M. Baratella, T. Bensby, S. L. Martell, S. Randich, G. Tautvaišienė, E. J. Alfaro, L. Morbidelli, R. Smiljanic and S. Zaggia
