First measurement of Mg isotope abundances at high redshifts and accurate estimate of Δα/α I. I. Agafonova, P. Molaro, S. A. Levshakov and J. L. Hou A&A, 529 (2011) A28 Published online: 25 March 2011 DOI: 10.1051/0004-6361/201016194