Sources: MoHM
- SLC to Unidentified, 9 May 1867 · New York, N.Y · UCCL10643
- SLC to George L. Fall, 28 November 1871 · Albany, N.Y · UCCL12695
- Samuel L. Clemens to Colton Greene, 26 April 1873 · Hartford, Conn · UCCL11885
- Samuel L. Clemens to John L. RoBards, 17 April 1876 · Hartford, Conn · UCCL01324
- Samuel L. Clemens to John L. RoBards, 10 June 1876 · Hartford, Conn · UCCL01341
- Samuel L. Clemens to Olivia L. Clemens, 5 August 1878 · Allerheiligen, Germany · UCCL01583
- SLC to Karl Gerhardt, 3 March 1881 · Hartford, Conn · UCCL08590
- SLC to James R. Osgood, 27 October 1881 · Hartford, Conn · UCCL09947
- SLC to John L. Robards, 2 August 1882 · Elmira, N.Y · UCCL02248
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