Goodin, Robert E.; Rice, James Mahmud; Parpo, Antti; Eriksson, Lina (2008). Discretionary Time: A New Measure of Freedom. Cambridge: Cambridge University Press. pp. 1–54. ISBN978-0-521-70951-4 Chapter 1 and 2 discusses the context and validity of the new measure.
Bronfenbrenner, Martin (1955). «Two Concepts of Economic Freedom». journal Ethics. 65 (3): 157–70. JSTOR2378928. doi:10.1086/290998
Sen, Amartya K. (1993). «Markets and Freedoms: Achievements and Limitations of the Market Mechanism in Promoting Individual Freedoms». Oxford Economic Papers. 45 (4): 519–541. doi:10.1093/oxfordjournals.oep.a042106