1. Archer, P.L., Kirr, J.N., 1984. Pennsylvanian geology, coal and coalbed methane resources of the Illinois Basin, Illinois, Indiana and Kentucky. In: Rightmire, C.T., Eddy, G.E., Kirr, J.N. (Eds.), Coalbed Methane Resources of the United States, AAPG Studies in Geology #17. Am. Assoc. of Petrol. Geol., Tulsa, OK, pp. 105–134.
2. Arps, J.J., 1962. Estimation of primary oil and gas reserves. In: Frick, T.C. (Ed.), Petroleum Production Handbook, Volume II. Soc. of Petrol. Eng., Dallas, TX, p. 37-10.
3. Averitt, P., 1981. Coal resources. In: Elliott, M.A. (Editor), Chemistry of Coal Utilization, Second Supplementary Volume. John Wiley & Sons, New York, NY, pp. 55–89.
4. Bai, Q., Zhang, X., Zhang, X., 1996. Coalbed methane resource evaluation of coal mining districts in China. Proc. of the CCMRI-International Mining Tech '96, Central Coal Min. Res. Inst., Beijing, pp. 172–192.
5. Boyer, C.M., 1994. International coalbed methane-where's the production? Presentation at the North American Coalbed Methane Forum, Morgantown, WV, 11 October 1994.