1. Germanium (2019) U.S. Geological Survey Germanium Statistics and Information.
https://prd-wret.s3-us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/atoms/files/mcs-2019-germa_0.pdf
. Accessed 22 July 2019
2. EU Critical materials list (2017) Third list of critical raw materials.
https://ec.europa.eu/growth/sectors/raw-materials/specific-interest/critical_en
. Accessed 22 July 2019
3. US Critical materials list (2018) Department of the Interior, Final list of Critical Minerals 2018.
https://www.usgs.gov/news/interior-releases-2018-s-final-list-35-minerals-deemed-critical-us-national-security-and
. Accessed 22 July 2019
4. Umicore Annual report (2018)
https://www.umicore.com/en/investors/financial-calendar/publication-of-the-annual-report-2018/c
. Accessed 21 Nov 2019
5. ISO (2006a) ISO 14040:2006, Environmental Management—Life Cycle Assessment—Principles and Framework