Sources: CBev6
- SLC to Unidentified, November 1870 · Buffalo, N.Y · UCCL12486
- Samuel L. Clemens to Emeline B. Beach, 4 February 1874 · Hartford, Conn · UCCL01044
- SLC to Lou W. Benjamin, 10 April 1886 · Hartford, Conn · UCCL03382
- SLC to William Smith, 3–4 February 1887 · Hartford, Conn · UCCL03522
- SLC to Marcel Schwob, 4 November 1888 · Hartford, Conn · UCCL12680
- SLC to Grace E. King, 30 April 1894 · New York, N.Y · UCCL04727
- SLC to Unidentified, 9 February 1895, Paris, France · UCCL14043
- SLC to William A. Wilson, 11 February 1895 · Paris, France · UCCL13412
- SLC to Francis H. Skrine, 19 January 1897 · London, England · UCCL05171
- SLC to Chatto & Windus, June 1897 · London, England · UCCL12707
- SLC to Unidentified, September 1902 · York Harbor, Maine · UCCL13519
- To Unidentified, 28 January 1906, Washington, D.C · UCCL14041
- SLC to Robert Reid, 30 April 1906 · New York, N.Y · UCCL07437
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