Sources: CLU-SC
- Samuel L. Clemens to Elisha Bliss, Jr., 31? May 1876 · Hartford, Conn · UCCL01337
- Samuel L. Clemens to A. M. Edwards, 8 December 1880 · Hartford, Conn · UCCL01868
- SLC to Unidentified, 16 May 1884 · Hartford, Conn · UCCL02980
- SLC to Joel Chandler Harris, Oliver Wendell Holmes, Frank R. Stockton and Charles Dudley Warner, 29 November 1885 · Hartford, Conn · UCCL03318
- SLC per Franklin G. Whitmore to MacKenzie Bell, 25 June 1890 · Hartford, Conn · UCCL04055
- SLC to Richard Watson Gilder, 13 January 1898 · Vienna, Austria · UCCL05167
- Clara L. Clemens to George R. Cole, 30 March 1898 · Vienna, Austria · UCCL05360
- Clara L. Clemens to George R. Cole, 2 April 1898 · Vienna, Austria · UCCL05356
- Clara L. Clemens to George R. Cole, 7 April 1898 · Vienna, Austria · UCCL05347
- Clara L. Clemens to George R. Cole, 8 April 1898 · Vienna, Austria · UCCL05359
- Clara L. Clemens to George R. Cole, 12 April 1898 · Vienna, Austria · UCCL05358
- Clara L. Clemens to George R. Cole, 14 April 1898 · Vienna, Austria · UCCL05357
- Clara L. Clemens to George R. Cole, 11 May 1898 · Vienna, Austria · UCCL10943
- SLC, OLC to Cornelius Cole, 17 May 1898 · Vienna, Austria · UCCL05390
- OLC to George R. Cole, 18 May 1898 · Vienna, Austria · UCCL05391
- SLC to John Adams, 5 December 1898 · Vienna, Austria · UCCL05159
- SLC to Unidentified, March 1899 · Vienna, Austria · UCCL09359
- SLC to Adela M. Goodrich-Freer, 11 January 1900 · London, England · UCCL05745
- SLC to C. E. Fagan, 17 June 1900 · London, England · UCCL05823
- SLC to Robert U. Johnson, 11 November 1900 · New York, N.Y · UCCL05901
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