1. Eberhard, A. (2011). The Future of South African Coal: Market, Investment, and Policy Challenges, Program on Energy and Sustainable Development; Freeman Spogli Institute for International Studies; Stanford University. Available online: https://fsi9-prod.s3.us-west-1.amazonaws.com/s3fs-public/WP_100_Eberhard_Future_of_South_African_Coal.pdf.
2. Makgae, M. (October, January 29). The Status and Implications of the AMD Legacy Facing South Africa. Proceedings of the International Mine Water Association Annual Conference, Bunbury, Australia. Available online: http://mwen.info/docs/imwa_2012/IMWA2012_Makgae_327.pdf.
3. Oelofse, S.H.H., Hobbs, P.J., Rascher, J., and Cobbing, J.E. (2007, January 11–13). The Pollution and Destruction Threat of Gold Mining Waste on the Witwatersrand—A West Rand Case Study. Proceedings of the 10th International Symposium on Environmental Issues and Waste Management in Energy and Mineral Production (SWEMP 2007), Bangkok, Thailand. Available online: https://www.anthonyturton.com/assets/my_documents/my_files/983_SWEMP.pdf.
4. What ended the great depression?;Romer;J. Econ. Hist.,1992
5. A description of how metal pollution occurs in the Tinto–Odiel rias (Huelva–Spain) through the application of cluster analysis;Grande;Mar. Pollut. Bull.,2003