ON THE INFLUENCE OF DEFECTS ON POSITRON ANNIHILATION IN ALKALI-HALIDES L. SMEDSKJAER, S. DANNEFAER, R. M. J. COTTERILL et G. TRUMPY J. Phys. Colloques, 34 C9 (1973) C9-97-C9-99 DOI: 10.1051/jphyscol:1973916