“…Coal rank Source peat Bird et al, 2004;Van Asselen et al, 2009;Van Asselen, 2011density lignite Falini, 1965Volkov, 1965lignite Glockner, 1912Ting, 1977inclusions bituminous Teichmüller, 1955Stach et al, 1975;Zaritsky, 1997;DeMaris et al, 1983;Gayer andPe ek, 1992 lignite Piwocki, 1975;Stout and Spackman, 1989;Hurník, 1990;Kojima et al, 1998;Widera, 2013asubbituminous White, 1986 indirect petrographic bituminous Courel, 1978;Winston, 1986peat Bloom, 1964Haslett et al, 1998lignite Hurník, 1972Hager et al, 1981;Hager, 1993;Kasi ski, 1984Kasi ski, , 1985Widera, 2002;Widera et al, 2007 direct stratigraphic bituminous this paper …”