Ultraviolet Variability of the Narrow-Line Seyfert 1 IRAS 13224-3809 Santos-Lleó, M. ; Rodríguez-Pascual, P. M. ; Mas-Hesse, J. M. Abstract Publication: Ultraviolet Astrophysics Beyond the IUE Final Archive Pub Date: 1998 Bibcode: 1998ESASP.413..619S