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