Konferenzbeitrag
Belloni, T.; Snowden, S. L.: A deep ROSAT observation of the highly variable AGN 1E1403+5439 - or ROSAT non-detection of the weak AGN 1E1403+5439. In: X-Ray Emission from Active Galactic Nuclei and the Cosmic X-Ray Background: Proceedings of a Conference held at the Max-Planck-Institut für extraterrestrische Physik, S. 187 - 190 (Hg.
Brinkmann, W.;
Trümper, J.). X-Ray Emission from Active Galactic Nuclei and the Cosmic X-Ray Background, Garching, Germany, 04. November 1991 - 08. November 1991. Max-Planck-Institut für extraterrestrische Physik, Garching, Germany (1992)