1. U.S. Energy Research and Development Administration, Hy-Gas: 1964 to 1972, Pipeline Gas from Coal, Research and Development Rep. No. 22 (Final), Vol. 1, p. 1–11, September 1972.
2. Gas from coal. Fuel of the future
3. “Catalytic Processes and Proven Catalysts,”;Thomas,1970
4. Aldridge, C. L., U.S. Patent No. 3,755,556 (1973).