Siebert, F. S., Peterson, T., & Schramm, W. (1963). Four theories of the press: The authoritarian, libertarian, social responsibility and soviet communist concepts of what the press should be and do. University of Illinois Press.

Siebert, Fred S., Theodore Peterson, and Wilbur Schramm. Four Theories of the Press: The Authoritarian, Libertarian, Social Responsibility and Soviet Communist Concepts of What the Press Should Be and Do. Urbana: University of Illinois Press, 1963.

Siebert, Fred S., et al. Four Theories of the Press: The Authoritarian, Libertarian, Social Responsibility and Soviet Communist Concepts of What the Press Should Be and Do. University of Illinois Press, 1963.