MAGNETIC PROPERTIES OF AMORPHOUS MANGANESE ALUMINOSILICATES : SPIN-GLASS LIKE BEHAVIOUR AT LOW TEMPERATURE J.P. Renard, J. Pommier, J. Ferre et K. Knorr J. Phys. Colloques, 39 C6 (1978) C6-936-C6-938 DOI: 10.1051/jphyscol:19786415