APA (7th ed.) Citation

Black, C. E., & Helmreich, E. C. (1966). Twentieth century Europe : a history / C.E. Black and E.C. Helmreich: A history (3rd ed.). Knopf.

Chicago Style (17th ed.) Citation

Black, Cyril E., and Ernst C. Helmreich. Twentieth Century Europe : A History / C.E. Black and E.C. Helmreich: A History. 3rd ed. New York: Knopf, 1966.

MLA (9th ed.) Citation

Black, Cyril E., and Ernst C. Helmreich. Twentieth Century Europe : A History / C.E. Black and E.C. Helmreich: A History. 3rd ed. Knopf, 1966.

Warning: These citations may not always be 100% accurate.