MÖSSBAUER ELECTRIC FIELD AND MEAN SQUARE DISPLACEMENT IN NATURALLY OCCURING FeS2 (PYRITE) SINGLE CRYSTALS R. Garg, V.P. Gupta et V.K. Garg J. Phys. Colloques, 41 C1 (1980) C1-355-C1-356 DOI: 10.1051/jphyscol:19801133