?. Dudley and K. , The Global Rare Earths Industry: A Delicate Balancing Act, Deutsche Rohstoffagentur, pp.16-2012

. ?2?-extrade and . Project, brgm.fr/ ?3? Gareth P Hatch, the Rare-Earth Supply-Chain Challenge: Light at the End of the Tunnel, Magnetics, vol.2013, 2013.