Cita APA (7th ed.)
Eibling, H. H., & Jackson, C. J. (1977). Two centuries of progress: United States history. Laidlaw brothers.
Cita Chicago (17th ed.)
Eibling, Harold H., i Carlton J. Jackson. Two Centuries of Progress: United States History. Irvine: Laidlaw brothers, 1977.
Cita MLA (9th ed.)
Eibling, Harold H., i Carlton J. Jackson. Two Centuries of Progress: United States History. Laidlaw brothers, 1977.
Atenció: Aquestes cites poden no estar 100% correctes.