1. Schernikau, L., Economics of the International Coal Trade: Why Coal Continues to Power the World, Cham: Springer, 2016, 2nd ed.
2. Speight, J.G., The Chemistry and Technology of Coal, Boca Raton: CRC Press, 2013, 3rd ed.
3. Maloletnev, A.S. and Artemova, N.I., Khim. Tverd. Topl. (Moscow), 2010, no. 4, p. 44.
4. Ali, A. and Zhao, C., Chin. J. Catal., 2020, vol. 41, no. 3, p. 375. https://doi.org/10.1016/S1872-2067(19)63492-3
5. Snape, C.E., Coal in the 21st Century: Energy Needs, Chemicals and Environmental Controls, Hester, R.E. and Harrison, R.M., Eds., London: The Royal Society of Chemistry, 2018, p. 173.