APA (7th ed.) Citation

Thomas, H. (1981). An unfinished history of the world (Rev. ed.). Pan Books.

Chicago Style (17th ed.) Citation

Thomas, Hugh. An Unfinished History of the World. Rev. ed. London: Pan Books, 1981.

MLA (9th ed.) Citation

Thomas, Hugh. An Unfinished History of the World. Rev. ed. Pan Books, 1981.