APA (7th ed.) Citation

Twain, M. Mark Twain's letters (Approved ed.). Univ. of California Press.

Chicago Style (17th ed.) Citation

Twain, Mark. Mark Twain's Letters. Approved ed. Berkeley u.a: Univ. of California Press.

MLA (9th ed.) Citation

Twain, Mark. Mark Twain's Letters. Approved ed. Univ. of California Press.