1. Schopf JM. A definition of coal. Economic Geology. 1956;51:521-527
2. Aplan FF. Coal flotation. In: Fuerstenau MC, editor. Flotation. A.M. Gaudin Memorial Volume. New York: AIME; 1976
3. Brown DJ. Coal flotation. In: Fuerstenau DW, editor. Froth Flotation, 50th Anniversary Volume. New York: AIME; 1962. pp. 518-538
4. Stonestreet P. Reverse flotation: A novel process for the beneficiation of fine coal [PhD thesis]. University of Cape Town; 1991. 275 p
5. Campbell JAL, Sun SC. An Electrokinetic Study of Bituminous Coal Froth Flotation and Flocculation, Special Report SR-74. Pennsylvania State University, University Park, Pennsylvania: Department of Mineral Preparation College of Earth and Mineral Science; 1969