The Mg II λ2797, λ2803 emission in low-metallicity star-forming galaxies from the SDSS N. G. Guseva, Y. I. Izotov, K. J. Fricke and C. Henkel A&A, 555 (2013) A90 Published online: 05 July 2013 DOI: 10.1051/0004-6361/201221010