- Mark Twain's Letters — Complete (1853-1910)
- Mark Twain's Letters — Volume 1 (1853-1866)
- Mark Twain's Letters — Volume 2 (1867-1875)
- Mark Twain's Letters — Volume 3 (1876-1885)
- Mark Twain's Letters — Volume 4 (1886-1900)
- Mark Twain's Letters — Volume 5 (1901-1906)
- Mark Twain's Letters — Volume 6 (1907-1910)