On the magnetic properties of B2O3-Pbo-Fe2O 3-K2O and B2O3-PbO-Fe 2O3-CaO glasses E. Burzo, D. Ungur et I. Ardelean J. Phys. France, 44 5 (1983) 647-650 DOI: 10.1051/jphys:01983004405064700