1. Froth flotation of low rank coals;Allum;J. Inst. Fuel,1954
2. K.J., Miller, Flotation study of refractory coals, Report of Investigations 8224, US Bureau of Mines, 1977.
3. Effects of surface functional groups on the flotation of coal;Fuerstenau;Colloids Surf.,1983
4. Effect of surface oxidation on the flotation of coals of different rank;Stachurski,1990
5. Froth flotation of coal;Hindmarch;Trans. Inst. Min. Eng.,1951