1. Walsh, A., Sokol, A. A., Buckeridge, J., Scanlon, D. O. & Catlow, C. R. A. Oxidation states and ionicity. Nat. Mater. 17, 958–964 (2018).
2. Jensen, W. B. The origin of the oxidation-state concept. J. Chem. Educ. 84, 1418 (2007).
3. Wöhler, F. Grundriss Der Chemie: Unorganische Chemie 3rd edn, 4 (Duncker & Humblot, 1835).
4. Latimer, W. M. The Oxidation States of the Elements and Their Potentials in Aqueous Solutions (Prentice-Hall Chemistry Series) 2nd edn (Prentice-Hall, 1952).
5. Connelly, N. G., Damhus, T., Hartshorn, R. M. & Hutton, A. T. (eds.) Nomenclature of Inorganic Chemistry. IUPAC Recommendations 2005 (RSC and IUPAC, 2005).