1. Spectrochemical analysis of coal ash for trace elements;Abernethy;U.S. Bur. Mines Rep. Invest.,1969
2. Copper in the peat bog formations of the Middle Ural;Al'bov;Sov. Geol.,1968
3. A preliminary study of the Brandon Lignites;Barghoorn;Amer. J. Sci.,1949
4. An investigation of the minecology, petrography and paleobotany of uranium-bearing lignites;Bates;Tech. Rep. NYO-7950 USAEC,1960
5. Organic geochemistry of Okefenokee peats: metal constituents;Casagrande,1974