61Ni MÖSSBAUER EFFECT STUDIES OF THE FERRIMAGNETIC SPINEL NiCr2O4 IN AN APPLIED MAGNETIC FIELD P. Gütlich, H. Rummel et H. Spiering J. Phys. Colloques, 41 C1 (1980) C1-185-C1-186 DOI: 10.1051/jphyscol:1980154