APA (7th ed.) Citation

Palmer, R. R. (1956). A history of the modern world (2nd ed., rev.). Knopf.

Chicago Style (17th ed.) Citation

Palmer, Robert Roswell. A History of the Modern World. 2nd ed., rev. New York: Knopf, 1956.

MLA (9th ed.) Citation

Palmer, Robert Roswell. A History of the Modern World. 2nd ed., rev. Knopf, 1956.