1. D.E. Hulse, D. Malhotra, T. Matthews, C. Emanuel, NI 43-101 Preliminary Economic Assessment Round Top Project Sierra Blanca, Texas: USA Rare Earth LLC and Texas Mineral Resources Corp (Gustavson Associates, 2019), p. 230
2. G. Barakos, H. Mischo, A review of misleading methods and biased practices in evaluating the feasibility of rare earth mining projects, in 28th SOMP Annual Meeting and Conference, (GEAM – Associazione Georisorse e Ambiente, Torino, 2017)
3. M.S. Jaroni, B. Friedrich, P. Letmathe, Economical feasibility of rare earth mining outside China. Fortschr. Mineral. 9(10), 576 (2019)
4. K. Binnemans, P.T. Jones, K. Van Acker, B. Blanpain, B. Misra, D. Apeliean, Rare earth economics: the balance problem. JOM 65(7), 846–848 (2013)
5. K. Binnemans, P.T. Jones, Rare earths and the balance problem. J. Sustain. Metall. 1(1), 29–38 (2015)