APA (7th ed.) Citation

Olby, R. C. (1974). Companion to the history of modern history. Routledge.

Chicago Style (17th ed.) Citation

Olby, R. C. Companion to the History of Modern History. London: Routledge, 1974.

MLA (9th ed.) Citation

Olby, R. C. Companion to the History of Modern History. Routledge, 1974.

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