I. The Crystal Structures of Iodic Acid and of Potassium Oxyfluoiodate, and the Redetermination of the Parameters in Potassium Difluoride and Ammonium Bifluoride. II. The Internuclear Distance in the Fluorine Molecule and the Electron Diffraction Investigation of Tellurium Dibromide. III. The Determination of the Magnetic Anisotropy of Crystals