APA (7th ed.) Citation

Roosevelt, T., Hay, J., Trevelyan, S. G. O., & Gray, D. (1954). Cowboys and kings: Three great letters. Harvard University Press.

Chicago Style (17th ed.) Citation

Roosevelt, Theodore, John Hay, Sir George Otto Trevelyan, and David Gray. Cowboys and Kings: Three Great Letters. Cambridge: Harvard University Press, 1954.

MLA (9th ed.) Citation

Roosevelt, Theodore, et al. Cowboys and Kings: Three Great Letters. Harvard University Press, 1954.