VALENCE DETERMINATION IN EuM2X2 COMPOUNDS : LIII-EDGE VERSUS MÖSSBAUER ISOMER SHIFT G. WORTMANN, B. PERSCHEID and W. KRONE J. Phys. Colloques, 47 C8 (1986) C8-979-C8-982 DOI: 10.1051/jphyscol:19868188