1. Study on removal characteristics of mineral matter from coal by physical separation. (1st Report). Mineral Composition of Coals and their Minimum Ash Content Attainable by Gravity Separation.
2. 2) Feely, T. J., Barnett, W. P. and Hucko, R. E. (1994):Preprints of 12th international coal preparation congress, Cracow (Poland). Vol. 1, p. 369-378
3. 4) Gluskoter, H. J., Rich, R., Miller, W. G., Cahill, R. A., Dreher, G. B. and Kuhn, J. K. (1977) : Illinois State Geological Survey Circular 499, p. 153
4. 5) Hower, J. C., Taulbee, D. N., Rimmer, S. N. and Morrell, L. G. (1944) : Energy & Fuels, Vol. 8, p. 719-728