Sources: TxU-Hu
- Samuel L. Clemens to Horatio G. Phillips, 29 October 1861 · Carson City, Nev. Terr · UCCL00032
- Samuel L. Clemens to William Bowen, 7 May 1866 · Island of Maui, Sandwich Islands · UCCL00100
- Samuel L. Clemens to William Bowen, 25 August 1866 · San Francisco, Calif · UCCL00106
- Samuel L. Clemens to William Bowen, 7 June 1867 · New York, N.Y · UCCL00133
- Samuel L. Clemens to Daniel Slote, 7 August 1867 · Naples, Italy · UCCL00143
- Samuel L. Clemens to William Bowen, 25 January 1868 · New York, N.Y · UCCL00184
- Samuel L. Clemens to William Bowen, 6 February 1870 · Buffalo, N.Y · UCCL02464
- Samuel L. Clemens to James Redpath, 7–8 July 1871 · Elmira, N.Y · UCCL00632
- Samuel L. Clemens to William Bowen, 17 January 1873 · Hartford, Conn · UCCL00858
- Samuel L. Clemens to William Bowen, 20 March 1873 · Hartford, Conn · UCCL00888
- Samuel L. Clemens to William Bowen, 28 March 1873 · Hartford, Conn · UCCL00891
- Samuel L. Clemens to William Bowen, 7 November 1873 · Hartford, Conn · UCCL00981
- Samuel L. Clemens to John Colborne, per Charles Warren Stoddard, 16 December 1873 · London, England · UCCL01008
- Samuel L. Clemens to William Bowen, 25 February? 1874 · Hartford, Conn · UCCL01054
- Samuel L. Clemens to James Redpath, 28 December 1874 · Hartford, Conn · UCCL01170
- Samuel L. Clemens to P. T. Barnum, 3 February 1875 · Hartford, Conn · UCCL01188
- Samuel L. Clemens to William Bowen, 20 March 1875 · Hartford, Conn · UCCL11467
- Samuel L. Clemens to Staff of the Hartford Courant, 13 September 1875 · Hartford, Conn · UCCL01259
- Samuel L. Clemens to James Cowan, 9 December 1879 · Hartford, Conn · UCCL01735
- Samuel L. Clemens to David Watt Bowser, 20 March 1880 · Hartford, Conn · UCCL01772
- Samuel L. Clemens to David Watt Bowser, 1? April 1880 · Hartford, Conn · UCCL01777
- Samuel L. Clemens to David Watt Bowser, 22 December 1880 · Hartford, Conn · UCCL02124
- SLC to James R. Osgood, 19 October 1881 · Hartford, Conn · UCCL02056
- SLC to David Watt Bowser, 16 November 1881 · Hartford, Conn · UCCL02087
- SLC to David Watt Bowser, 10 January 1882 · Hartford, Conn · UCCL02147
- SLC to E. B. Peck, 11 February 1882 · Hartford, Conn · UCCL02158
- SLC to George Iles, 14 December 1883 · Hartford, Conn · UCCL12258
- SLC to Edgar W. Howe, 20 April 1884 · Hartford, Conn · UCCL02961
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