Van Der Helm, D.; Merritt, L. L.; Degeilh, R.; MacGillavry, C. H. The Crystal Structure of IIron Cupferron Fe(O2N2C6H5)3. Acta Crystallographica. 1965, 18 (3): 355–362. doi:10.1107/S0365110X65000816.
Mark, Wanda; Aava, Ulf; Haaland, A.; Resser, Dag; Rasmussen, S. E.; Sunde, Erling; Sørensen, Nils Andreas. The Crystal Structure of Zirconium Cupferrate, Zr(C6H5N2O2)4. Acta Chemica Scandinavica. 1970, 24: 1398–1414. doi:10.3891/acta.chem.scand.24-1398.
D. Van der Helm, L. L. Merritt Jnr, R. Degeilh and C. H. MacGillavry "The crystal structure of iron cupferron Fe(O2N2C6H5)3" Acta Crystallogr. (1965). 18, 355–362