1. Ahmed, H.A.M., 2005, Application of microemulsion for upgrading difficult-to-float materials, Ph. D. thesis, Wroclaw Technical University.
2. Ahmed, H.A.M., and Drzymala, J., 2004, “Effect of flotation procedure and composition of reagents on yield of a difficult-to-float coal,” Physicochemical Problems of Mineral Processing, Vol. 38, pp. 53–63.
3. Becher, P., Emulsions: Theory and Practice, Krieger Pub., 1977.
4. Bolat, E., Saglam, S., and Piskin, S., 1998, “Effect of oxidation on the flotation properties of a Turkish bituminous coal,” Fuel Processing Technology, Vol. 55, No. 2, pp. 101–105.
5. Buttermore, W.H., and Slomka, B.J., 1991, “Effect of sonic treatment on the float-ability of oxidized coal,” Int. J. Miner. Process., Vol. 32, No. 3–4, pp. 251–257.