1. NaturalGas.org. [accessed 10.02.11].
2. The theory of demand applied to the French gas industry;Verhulst;Econometrica,1950
3. Energy from fossil fuels;Hubbert;Science,1949
4. Hubbert MK. Nuclear energy and the fossil fuels. Presented before the spring meeting of the Southern District Division of Production, American Petroleum Institute, San Antonio, TX, March 8, 1956. Publication No. 95. Houston: Shell Development Company, Exploration and Production Research Division, June, 1956. 5. Worldwide supply and demand of petroleum liquids;Al-Jarri;Proc SPE Ann Tech Conf Exhibit,1997