Milky Way metallicity gradient from Gaia DR2 F/1O double-mode Cepheids B. Lemasle, G. Hajdu, V. Kovtyukh, L. Inno, E. K. Grebel, M. Catelan, G. Bono, P. François, A. Kniazev, R. da Silva and J. Storm A&A, 618 (2018) A160 Published online: 26 October 2018 DOI: 10.1051/0004-6361/201834050