APA (7th ed.) Citation

Thornton, A. P. (1977). Imperialism in the twentieth century. University of Minnesota Press.

Chicago Style (17th ed.) Citation

Thornton, A. P. Imperialism in the Twentieth Century. Minneapolis: University of Minnesota Press, 1977.

MLA (9th ed.) Citation

Thornton, A. P. Imperialism in the Twentieth Century. University of Minnesota Press, 1977.