APA (7th ed.) Citation
Twain, M., & De Voto, B. A. (1977). The portable Mark Twain. Penguin Books.
Chicago Style (17th ed.) Citation
Twain, Mark, and Bernard Augustine De Voto. The Portable Mark Twain. New York: Penguin Books, 1977.
MLA (9th ed.) Citation
Twain, Mark, and Bernard Augustine De Voto. The Portable Mark Twain. Penguin Books, 1977.
Warning: These citations may not always be 100% accurate.