Hollmann, N., Valldor, M., Wu, H., Hu, Z., Qureshi, N., Willers, T., et al. (2011). Orbital occupation and magnetism of tetrahedrally coordinated iron in CaBaFe4O7. Physical Review B, 83(18): 180405, pp. 180405-1-180405-4. doi:10.1103/PhysRevB.83.180405.