Optical measurements of the superconducting gap in MgB2 B. Gorshunov, C. A. Kuntscher, P. Haas, M. Dressel, F. P. Mena, A. B. Kuz'menko, D. van der Marel, T. Muranaka and J. Akimitsu Eur. Phys. J. B, 21 2 (2001) 159-161 Published online: 15 May 2001 DOI: 10.1007/s100510170191