AN EXPERIMENTAL TEST OF THE RIGID-MUFFIN-TIN APPROXIMATION USED IN THE THEORY OF ELECTRON-PHONON INTERACTION W. Ruesink, J. de Wilde, R. Griessen and M.J.G. Lee J. Phys. Colloques, 39 C6 (1978) C6-1097-C6-1098 DOI: 10.1051/jphyscol:19786486