1. Information available from the UHDE website: www.uhde.biz, The Shell Gasification Process, Aug. 10, 2005.
2. General information from the website for Shell Gas and Power; internet website: www.shell.com, Aug. 1, 2005.
3. N. Richter: Introduction to Gasification (ChevronTexaco), internet website: www.gasification.org/Docs/02Richter.pdf, Aug. 2, 2005.
4. W.A. Selvig and F.H. Gibson: USBM Bull. Pub., 1956, vol. 567, pp. 1–33.
5. S.V. Vassilev, C. Braekman-Danheux, R. Moliner, I Suelves, M. J. Lázaro, and T. Thiemann: Fuel, 2002, vol. 81, pp. 1281–96.