1. Retcofsky, H.L. 1977, Appl. Spectr. 31, p. 116.
2. Gerstein, B.C., Ryan, L.M., and Murphy, P.D. 1981, “Coal Structure,” Eds. M.L. Gorbaty and K. Ouchi, ACS 192, Washington, D.C.
3. Bartuska, V.S., Maciel, G.E., Schaefer, J., and Stejskal, E.O. 1977, FUEL 56, p. 354.
4. Lefelhocz, J.F., Friedel, R.A., and Kohman, T.P. 1967, Geochim. Cosmochim. Acta. 31, p. 2261.
5. Montano, P. A. 1977, FUEL 56, p. 397.