HAMRLA, M. Petrographical composition of some specimens of Raša coal, regarding their varying coking ability. Geologija, [S. l.], v. 3, n. 1, p. 181–197, 1955. Disponível em: https://www.geologija-revija.si/index.php/geologija/article/view/173. Acesso em: 19 may. 2024.