SURFACE-EXCHANGE MODES IN FERROMAGNETIC PARTICLES AND THIN FILMS G. HEBER, F. GOEDSCHE, E. HEINER, J. MONECKE and H. WENZEL J. Phys. Colloques, 32 C1 (1971) C1-1165-C1-1167 DOI: 10.1051/jphyscol:19711417