1. W. L. Lom and A. F. Williams, Substitute Natural Gas, Applied Science Publishers, London, 1976
2. T. Gold and S. Soter, ‘The deep-earth-gas hypothesis’, Scientific American, Vol. 242, June 1980, pp. 154–62
3. W. L. Lom, Liquefied Natural Gas, Applied Science Publishers, London, 1974
4. K. E. Cox and K. D. Williamson, Hydrogen: its Technology and Implications. Vol. 1, Hydrogen production technology, CRC Press, Cleveland, Ohio, 1977
5. Symposium on Hydrogen in Air Transportation, DGLV/DFVLR, Stuttgart, September 1979