APA (7th ed.) Citation

Twain, M., & Leary, L. (1961). Mark Twain's Letters to Mary. Columbia University Press.

Chicago Style (17th ed.) Citation

Twain, Mark, and Lewis Leary. Mark Twain's Letters to Mary. New York: Columbia University Press, 1961.

MLA (8th ed.) Citation

Twain, Mark, and Lewis Leary. Mark Twain's Letters to Mary. Columbia University Press, 1961.