APA (7th ed.) Citation

Twain, M. Mark Twain's Letters — Complete (1853-1910).

Chicago Style (17th ed.) Citation

Twain, Mark. Mark Twain's Letters — Complete (1853-1910).

MLA (9th ed.) Citation

Twain, Mark. Mark Twain's Letters — Complete (1853-1910).

Warning: These citations may not always be 100% accurate.