1. Roubíček V, Buchtele J (2002) Coal. Sources, processes, application (in Czech). Montanex, Ostrava
2. Sýkorová I, Novotná M, Pavlíková H, Machovič V (1996) In: Gayer R, Harris I (eds) Coalbed Methane and Coal Geology. Geological Society Spec Publ., London, p 249
3. Mikulášková B, Lapčík L, Mašek I (1997) Chem Listy 91:160
4. Khungar SC (1998) Fertil News 43:67
5. Pekař M, Klučáková M (2003) CHEMagazin 13:8