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2. H.H. Schobert, F.R. Karner, D.R. Kleesattel, and E.S. Olson, Characterization of the lithologic layers of North Dakota lignites, Proceedings 1985 International Conference on Coal Science, pp. 608–611.
3. New approaches to the characterization of lignites: A combined geological and chemical study;Schobert,1987
4. Pyrolysis and devolatilization;Ross;University of North Dakota Energy Research Center monthly report,1986
5. Distribution of inorganics;Hurley;University of North Dakota Energy Research Center monthly report,1985