1. Białecka, B. (2008). Estimation of coal reserves for UCG in the Upper Silesian Coal Basin, Poland. Natural Resources Research, 17, 21–28.
2. Blinderman, MS. (2005). The Exergy UCG technology and its application in commercial clean coal projects. In: Second international conference on clean coal technologies for our future. Sardinia, Italy.
3. Burgess, S. (2011). Some bore contaminants from agricultural source: report. ABC News. http://www.abc.net.au/news/2011-11-01/some-bore-contaminants-from-agricultural-source-report/3612234?section=business . Accessed March 2012.
4. Burton, E., Friedmann, J., Upadhye R. (2006). Best practices in underground coal gasification. Report under contract No. W-7405-Eng-48, Lawrence Livermore National Laboratory, University of California, USA.
5. Collins, J. F., Brown, J. P., Alexeeff, G. V., & Salmon, A. G. (1998). Potency equivalency factors for some polycyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbon derivatives. Regulatory Toxicology and Pharmacology, 28, 45–54.