Clark, G. (1990). Outline of the U S Economy. United States Department of State.
Cita Chicago (17th ed.)Clark, George. Outline of the U S Economy. United States Department of State, 1990.
Cita MLA (9th ed.)Clark, George. Outline of the U S Economy. United States Department of State, 1990.
Atenció: Aquestes cites poden no estar 100% correctes.