1. Cope, M.J. (1979) In: A.G. Douglas and J.R. Maxwell Advances in Organic Geochemistry (Eds.), 663p.
2. Davis, M.R., White, A. and Deegn, M.D. (1986) Scanning electron microscopy of coal macerals. Fuel, v.65, pp.277–280.
3. Garin-valles, M., Pradell, T., Martinez, S. and Vendrell, M. (1993) Mineralogical characterization of the Garumnian subbituminous lignite from the central Pyrenees by SEM-EDX, X-ray diffraction and Mössbauer spectroscopy. Fuel, v.72, pp.971–975.
4. Gluskoter, H.J., Shimp, N.F. and Ruch, R.R. (1981) In: M.A. Elliott (Ed.), Chemistry of coal Utilization. 2nd supplementary volume, Wiley, New York, 413p.
5. Himus, G.W. (Ed.) (1954) Fuel testing: laboratory methods in fuel technology. Leonard Hill, London, pp.67–78