Sources: MWA
- Samuel L. Clemens to Unidentified, November 1880 · Unknown place · UCCL09311
- SLC to Sarah K. Bolton, 23 October 1886 · Hartford, Conn · UCCL01973
- SLC to Sarah K. Bolton, 3 November 1886 · Hartford, Conn · UCCL02005
- SLC to Sarah K. Bolton, 13 November 1886 · Hartford, Conn · UCCL01976
- SLC to Sarah K. Bolton, 7 July 1887 · Elmira, N.Y · UCCL02106
- SLC to Sarah K. Bolton, 20 September 1888 · Elmira, N.Y · UCCL05042
- SLC to Clarence W. Bowen, 8 April 1889 · Hartford, Conn · UCCL03881
- SLC to Clarence W. Bowen, 28 April 1889 · Hartford, Conn · UCCL03887
- SLC to Charles H. Taylor, 25 October 1889 · Hartford, Conn · UCCL03957
- SLC to Clarence W. Bowen, 24 January 1890 · Hartford, Conn · UCCL04006
- SLC to Thomas L. Gulick, 8 January 1891 · Hartford, Conn · UCCL04155
- SLC to Joseph H. Twichell, 9 October 1893 · New York, N.Y · UCCL04471
- SLC to Charles H. Taylor, 1 October 1901 · Riverdale, N.Y · UCCL06151
- SLC to Sarah K. Bolton, Unknown date · Unknown place · UCCL05007
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