APA (7th ed.) Citation

Twain, M. (1990). The adventures of Huckleberry Finn (Tom Sawyer's Comrade). Project Gutenberg.

Chicago Style (17th ed.) Citation

Twain, Mark. The Adventures of Huckleberry Finn (Tom Sawyer's Comrade). Champaign, Ill: Project Gutenberg, 1990.

MLA (9th ed.) Citation

Twain, Mark. The Adventures of Huckleberry Finn (Tom Sawyer's Comrade). Project Gutenberg, 1990.