APA (7th ed.) Citation

Nicolay, J. G., & Hay, J. M. (1914). Abraham Lincoln: A history. The Century Co.

Chicago Style (17th ed.) Citation

Nicolay, John G., and John Milton Hay. Abraham Lincoln: A History. New York: The Century Co, 1914.

MLA (9th ed.) Citation

Nicolay, John G., and John Milton Hay. Abraham Lincoln: A History. The Century Co, 1914.