APA (7th ed.) Citation

Twain, M., & DeVoto, B. (1965). The portable. The Viking Press.

Chicago Style (17th ed.) Citation

Twain, Mark, and Bernard DeVoto. The Portable. New York: The Viking Press, 1965.

MLA (9th ed.) Citation

Twain, Mark, and Bernard DeVoto. The Portable. The Viking Press, 1965.