Msila, Xolani, Frans Labuschagne, Werner Barnard, and David G. Billing. “Radioactive Nuclides in Phosphogypsum from the Lowveld Region of South Africa”.
South African Journal of Science 112, no. 1/2 (February 1, 2016): 5. Accessed April 3, 2025.
https://sajs.co.za/article/view/4154.