[en] Z And is considered as the ''prototype'' of the symbiotic stars. Besides its symbiotic spectrum, the star is also known for its characteristic light curve (and for the related spectral variations). Since many theoretical speculations on Z And and similar objects have been based on the luminosity and spectral variations of this star, the authors critically analyse the observational data concerning it. (Auth.)

[en] The high resolution ultraviolet spectrum of AG Dra was observed with IUE in April and August 1981 at phases 0.50 and 0.69 according to the Meinunger (1979) U-light curve. The UV spectrum of the star appears rather different from that of the other classical symbiotic stars and is briefly discussed. The authors have also compared the 1981 observations with the pre-outburst 1979 (phase 0.46) and 1980 (phase 0.90) IUE spectra. The continuum and the emission lines before outburst appeared much weaker than in 1981, and the 1979-80 variations are in agreement with the Meinunger light curve, suggesting that the whole UV spectrum of AG Dra before outburst is variable in phase with the U-curve. (Auth.)

[en] High and low resolution IUE spectra of CI Cyg were obtained at VILSPA during 1979-81 allowing for an analysis of the spectral variations related to the decreasing activity of the star, and to the eclipse (June 1980). (Auth.)