1. Semaw, S., et al.: 2.5-million-year-old stone tools from Gona, Ethiopia. Nature 385, 333–336 (1997)
2. Furberg, A., Arvidsson, R., Molander, S.: Environmental life cycle assessment of cemented carbide (WC-Co) production. J. Clean. Prod. 209, 1126–1138 (2019)
3. Al Barazi, S.: Rohstoffrisikobewertung – Kobalt. DERA Rohstoffinformationen 36. Deutsche Rohstoffagentur (DERA) in der Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Berlin (2018)
4. European Commission: Report on Critical Raw Materials and the Circular Economy, Brussels (2018)
5. Werner, A.B.T.; Sinclair, W.D.; Amey, E.B.: International strategic mineral issues summary report – Tungsten (Ver. 1.1, November 2014). U.S. Geological Survey Circular 930-O. U.S. Department of the Interior, Reston (2014)