Influence of metallicity on the near-surface effect on oscillation frequencies L. Manchon, K. Belkacem, R. Samadi, T. Sonoi, J. P. C. Marques, H.-G. Ludwig and E. Caffau A&A, 620 (2018) A107 Published online: 05 December 2018 DOI: 10.1051/0004-6361/201833783