1. Climate Action Plan 2050 2016 www.bmub.bund.de/fileadmin/Daten_BMU/Download_PDF/Klimaschutz/klimaschutzplan_2050_kurzf_en_bf.pdf
2. China - Measures Related to the Exportation of Rare Earths, Tungsten, and Molybdenum 2014
3. China - Duties and Other Measures Concerning the Exportation of Certain Raw Materials 2016
4. M. Stürmer J. von Hagen DERA Rohstoffinformationen 2012