1. Ketchum, R., A Report of the Utah Conservation and Research Foundation to the Governor and State Legislature, May 1939.
2. Carbonization by-products, http://www.solidfuel.co.uk/frame/main.html
3. McHenry, E.R., Coal-tar/ Petro industrial pitches, Koppers Industries, 1005 Wm. Pitt Way, Pittsburgh, PA 15238.
4. Lewis, I.C., Chemistry of carbonization, Carbon, 1982, vol. 20, no. 6, pp. 519–529.
5. Loison, R., Foch, P., and Boyer, A., Coke Quality and Production, Butterworth & Co, 1989.