1. Van Krevelen DW, (1993) Coal: Typology-physics-chemistry-constitution. Elsevier Science
2. Berkowitz N (1979) An introduction to coal technology. Academic Press
3. Hillr H, Reimert R, Marschner F, Renner HJ, Boll W, Supp E, Brejc M, Liebner W, Schaub G, Hochgesand G, Higman C, Kalteier P, Muller WD, Kriebel M, Schlichting H, Tanz H, Stonner HM, Klein H, Hilin W, Gronemann V, Zwiefelhofer U, Albrecht J, Cowper CJ, Driesen HE (2000) Gas production, in Ullmann’s Encyclopedia of industrial chemistry, Wiley-VCH Verlag GmbH
4. Morehead H (2013) Siemens gasification: progress and innovation. In Proceedings of the gasification technologies conference, 13–16 Oct 2013, Colorado Springs, CO. www.gasification.org
5. Petrakis L, Grandy DW (1981) Formation and behaviour of coal free radicals in pyrolysis and liquefaction conditions. Nature 289:476–477