APA (7th ed.) Citation

Black, C. E., & Helmreich, E. C. (1950). Twentieth century Europe: A history ([1st ed.].). Knopf.

Chicago Style (17th ed.) Citation

Black, Cyril Edwin, and Ernst Christian Helmreich. Twentieth Century Europe: A History. [1st ed.]. New York: Knopf, 1950.

MLA (9th ed.) Citation

Black, Cyril Edwin, and Ernst Christian Helmreich. Twentieth Century Europe: A History. [1st ed.]. Knopf, 1950.