1. Kukharenko, T.A., Khimiya i genezis iskopaemykh uglei (Chemistry and Genesis of Fossil Coals), Moscow: Gosgortekhizdat, 1960.
2. Kusov, B.R., Genezis nekotorykh uglerodsoderzhashchikh poleznykh iskopaemykh (Ot metana do almaza) (Genesis of Some Carbon-Containing Materials: From Methane to Diamond), Vladikavkaz: IPO SOIGSI, 2011, 2nd ed.
3. Charon, O., Kang, S.G., Sarofm, A.F., and Beer, J.M., Variation in Coal Composition.
http://www.anl.gov/PCS/acsfuel/preprintarchive/Files/Volumes/Vol. 34-2.pdf. Accessed February 9, 2022.
4. Titirici, M.M. and Antonietti, M., Chem. Soc. Rev., 2010, vol. 39, no. 1, p. 103.
5. Chen, J., Lang, Z., Xu, Q., Hu, B., Fu, J., Chen, Z., and Zhang, J., ACS Sustain. Chem. Eng., 2013, vol. 1, no. 8, p. 1063.