Sources: Mo4
- Samuel L. Clemens to Joseph H. Twichell, 12 December 1868 · Norwich, N.Y · UCCL02729
- Samuel L. Clemens to Jervis Langdon, 29 December 1868 · Cleveland, Ohio · UCCL00212
- Samuel L. Clemens to Joseph H. Twichell, 1 January 1869 · Cleveland, Ohio · UCCL00216
- Samuel L. Clemens to Joseph H. Twichell and Family, 23 January 1869 · Cleveland, Ohio · UCCL00240
- Samuel L. Clemens to Jane Lampton Clemens and Family, 5 February 1869 · Elmira, N. Y · UCCL00245
- Samuel L. Clemens to Joseph H. Twichell and Family, 14 February 1869 · Ravenna, Ohio · UCCL00252
- Samuel L. Clemens to Pamela A. Moffett, 10? April 1869 · Elmira, N. Y · UCCL00289
- Samuel L. Clemens to Elisha Bliss, Jr., 10? April 1869 · Elmira, N. Y · UCCL00288
- Samuel L. Clemens to Pamela A. Moffett, 20 and 21 August 1869 · Buffalo, N. Y · UCCL00336
- Samuel L. Clemens to Jane Lampton Clemens, 11 June 1871 · Elmira, N.Y · UCCL00615
- Samuel L. Clemens to Olivia L. Clemens, 28 October 1871 · Great Barrington, Mass · UCCL00667
- Samuel L. and Oliva L.Clemens to Mary E. (Mollie) Clemens, 20 or 21 July 1872 · New Saybrook, Conn · UCCL00775
- Samuel L. Clemens to Olivia L. Clemens, 20 August 1872 · New York, N.Y · UCCL00796
- Samuel L. Clemens to Olivia L. Clemens, 25 and 26 April 1873 · Hartford, Conn · UCCL00908
- Samuel L. Clemens to Olivia L. Clemens, 11 November 1879 (2nd of 2)· Chicago, Ill · UCCL01713
- SLC to OLC, 28 November 1881 · Montreal, Canada · UCCL11717
- SLC to OLC, 6 December 1881 · Montreal, Canada · UCCL02110
- SLC to OLC, 7 December 1881 · Montreal, Canada · UCCL02111
- OLC to SLC, 20 February 1885 · Hartford, Conn · UCCL03175
- OLC to SLC, 18 May 1890 · Hartford, Conn · UCCL08629
- OLC to SLC, 22 May 1890 · Hartford, Conn · UCCL08632
- SLC to OLC, 26 November–27 November 1890 · Hartford, Conn · UCCL08633
- OLC to SLC, 27 November 1890 · Elmira, N.Y · UCCL08630
- SLC to OLC · 28 September 1891 · (2nd of 2) · Avignon, France · UCCL11719
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