1. Bundesministerium für Wirtschaft, Energie Daten, 2000, p. 10.
2. ISO 6976 Natural Gas—Calculation of Calorific Values, Density, Relative Density and Wobbe Index from Composition, 2nd Edition, 1995 (corrected and reprinted in February 1996).
3. V.P. Kolesov, Bomb combustion of gaseous compounds in oxygen, in: S. Sunner, M. Månsson (Eds.), Experimental Chemical Thermodynamics, Vol. 1: Combustion Calorimetry, Pergamon Press, Oxford, 1979, pp. 1–16 (Chapter 13).
4. ASTM Standards on Gaseous Fuels, September 1958.
5. C.G. Hyde, M.W. Jones, Gas Calorimetry, 2nd Edition, Ernest Benn Ltd., London, 1960.