Sources: C4
- Samuel L. Clemens to Elizabeth W. Smith, 13? October 1859 · St. Louis, Mo · UCCL00021
- Samuel L. Clemens to John McComb, 8 June 1867 · New York, N.Y · UCCL00137
- Samuel L. Clemens to Elisha Bliss, Jr., 4 July 1870 · Elmira, N.Y · UCCL00486
- Samuel L. Clemens to the Staff of the Hartford Courant, 19 October 1875 · Hartford, Conn · UCCL01271
- Samuel L. Clemens to Henry Nason Kinney, 21 or 22 March 1876 · Hartford, Conn · UCCL00468
- Samuel L. Clemens to Unidentified, December 1880 · Hartford, Conn · UCCL01862
- SLC to C. L. Fleck, 6 February 1883 · Hartford, Conn · UCCL02343
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