1. Comparative characteristics of the ionospheres of the planets of the terrestrial group: Mars, Venus, and the Earth

   • K. I. Gringauz
   • T. K. Breus

   OriginalPaper Pages: 743 - 769

2. Characteristic γ- and X-radiation in the planetary system

   • Paul Gorenstein
   • Herbert Gursky

   OriginalPaper Pages: 770 - 829

3. The variable X-ray spectrum of Cyg XR-1

   • Joseph F. Dolan

   OriginalPaper Pages: 830 - 868