Cita APA (7a ed.)

O'Callaghan, B. (1987). A history of the Twentieth Century (1. publ.). Longman.

Cita Chicago Style (17a ed.)

O'Callaghan, Bryn. A History of the Twentieth Century. 1. publ. London [u.a.] New York: Longman, 1987.

Cita MLA (9a ed.)

O'Callaghan, Bryn. A History of the Twentieth Century. 1. publ. Longman, 1987.