Kalvig, Per, Rune J. Clausen, Niels Fold, and Karen Hanghøj. “To What Extent Is Denmark Vulnerable to Mineral Supply Shortage?”. GEUS Bulletin 31 (June 25, 2014): 95–98. Accessed May 31, 2023. https://geusbulletin.org/index.php/geusb/article/view/4672.