APA (7th ed.) Citation

Black, C. E., & Helmreich, E. C. (1966). Twentieth Century Europe: A history (3d ed.). Knopf.

Chicago Style (17th ed.) Citation

Black, Cyril Edwin, and Ernst Christian Helmreich. Twentieth Century Europe: A History. 3d ed. New York: Knopf, 1966.

MLA (9th ed.) Citation

Black, Cyril Edwin, and Ernst Christian Helmreich. Twentieth Century Europe: A History. 3d ed. Knopf, 1966.