Strong temperature effect on the sizes of the Cooper pairs in a two-band superconductor Teet Örd, Küllike Rägo, Artjom Vargunin and Grzegorz Litak Eur. Phys. J. B, 91 1 (2018) 2 Published online: 15 January 2018 DOI: 10.1140/epjb/e2017-80477-8