WEAK FERROMAGNETISM IN SINGLE CRYSTALS OF KMnF4.H2O AND (NH4) MnF4.2H2O F. Palacio, M. Andrés, D. van Noort and A. J. van Duyneveldt J. Phys. Colloques, 49 C8 (1988) C8-819-C8-820 DOI: 10.1051/jphyscol:19888368