  Based on high-spectral-resolution observations (R=60000) performed with the
6-m BTA telescope in combination with the echelle spectrograph NES, we have
studied the optical spectra of three A-type supergiants: a peculiar supergiant
3 Pup, a post-AGB star BD+48 1220, and a massive $\alpha$ Cyg, which belong to
essentially different stages of evolution. A spectral atlas for these stars is
prepared in the wavelength interval of 3920 to 6720 \AA.
