1. H. Freundlich, Kapillarchemie, Leipzig, 1909, p. 144.
2. A.W. Adamson, A.P. Gast, Physical Chemistry of Surfaces, John Wiley and Sons, Inc. New York, 1997.
3. C.J. Van Oss, Interfacial forces in aqueous media, Marcel Dekker, New York, 1994.
4. J.W. Gibbs, Collected Works, vol. 1, Yale University Press, 1948.