de Boer, J. H.; Verwey, E. J. W. (1937). "Semi-conductors with partially and with completely filled 3d-lattice bands". Proceedings of the Physical Society. 49 (4S): 59. Bibcode:1937PPS....49...59B. doi:10.1088/0959-5309/49/4S/307.
de Boer, J. H.; Verwey, E. J. W. (1937). "Semi-conductors with partially and with completely filled 3d-lattice bands". Proceedings of the Physical Society. 49 (4S): 59. Bibcode:1937PPS....49...59B. doi:10.1088/0959-5309/49/4S/307.