1. Brady, G.A. and Gauger, A.W., Properties of coal surfaces, J. Ind. Eng. Chem., 1940, vol. 32, pp. 1599–1604.
2. Horsley, R.M. and Smith, H.G., Principles of coal flotation, Fuel, 1951, vol. 30, pp. 54–63.
3. Klassen, V.I., Flotatsiya uglei (Coal Floatation), Moscow: Gosgortekhizdat, 1963.
4. Zimon, A.D., Adgeziya zhidkosti i smachivaniya (Adhesion of Liquid and Wetting), Moscow: Khimiya, 1974.
5. Gutierrez-Rodriguez, J.A., Purcell, R.J., and Aplan, F.F., Estimating the hydrophobicity of coal, Colloids Surfaces, 1984, vol. 12, pp. 1–25.