COLOUR CENTRES IN HALIDES (1).Electron spin resonance in different states of the relaxed configuration of F-centres A. Winnacker, K. Hahn, H. J. Reyher and Th. Vetter J. Phys. Colloques, 41 C6 (1980) C6-39-C6-41 DOI: 10.1051/jphyscol:1980610