OPTICAL REFLECTIVITY SPECTRA AND ELECTRONIC STRUCTURES IN Fe7Se8 AND Co7Se8 K. Sato, H. Kida, M. Fujisawa et T. Kamimura J. Phys. Colloques, 49 C8 (1988) C8-37-C8-38 DOI: 10.1051/jphyscol:1988807