Fizika Tverdogo Tela, 1991 Volume 33, Issue 1,Pages 182–186(Mi ftt6618)
Long-wavelength IR spectra of $\mathrm{Bi}_{2}\mathrm{Sr}_{2}\mathrm{Ca}_{0.6}\mathrm{Ba}_{0.4}\mathrm{Cu}_{1.9}\mathrm{O}_{x}$ in the glassy and crystalline (superconducting) states