1. Abramski, C., Mackowsky, M.-Th., Mantel, W., Stach, E., 1951. Atlas für angewandte Steinkohlenpetrographie. Glückauf, Essen, 329 pp.
2. Allerdice, D.J., Evans, D.G., 1978. Moisture in coal. In: Karr, C. (Ed.), Analytical Methods of Coal and Coal Products, Vol. 1. Academic Press, New York, pp. 247–262.
3. Sur le pouvoir réflecteur de la vitrinite et la fusinite des houilles;Alpern;C. R. Acad. Sci. Paris, Ser. D,1970
4. Sulfur in coal—geological aspects;Ashley;Am. Inst. Min. Eng. Trans.,1920
5. Limits of the natural environment in terms of pH and oxidation–reduction potential;Baas-Becking;J. Geol.,1960