- Warhurst, Chris; Keep, Ewart; Grugulis, Irena. The Skills That Matter. Palgrave. 2004-02-27: 242–260 (February 27, 2004) . ISBN 9781403906397.
- Capital, Volume 1, by Marx, Karl. From "Chapter 32: Historical Tendency of Capitalist Accumulation": "Self-earned private property, that is based, so to say, on the fusing together of the isolated, independent laboring-individual with the conditions of his labor, is supplanted by capitalistic private property, which rests on exploitation of the nominally free labor of others, i.e., on wage-labor. As soon as this process of transformation has sufficiently decomposed the old society from top to bottom, as soon as the laborers are turned into proletarians, their means of labor into capital, as soon as the capitalist mode of production stands on its own feet, then the further socialization of labor and further transformation of the land and other means of production into socially exploited and, therefore, common means of production, as well as the further expropriation of private proprietors, takes a new form. That which is now to be expropriated is no longer the laborer working for himself, but the capitalist exploiting many laborers."