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
- SLC to Unidentified, Unknown date, Hartford, Conn · UCCL12653
- SLC to Edward W. Bok, 30 August 1885 · Elmira, N.Y · UCCL03281
- SLC to Unidentified, 21 December 1886 · Hartford, Conn · UCCL03501
- SLC to Webster (C. L.) & Co., 29 December 1887 · Hartford, Conn · UCCL03687
- SLC to William Bowen, 6 October 1888 · Hartford, Conn · UCCL03783
- SLC to William Bowen, 4 November 1888 · Hartford, Conn · UCCL03826
- SLC to William Bowen, 29 December 1888 · Hartford, Conn · UCCL03810
- SLC to Richard Watson Gilder, 30 May 1889 · Unknown place · UCCL03897
- SLC to Henry M. Stanley, 18 June 1889 · Unknown place · UCCL03902
- SLC to Andrew Chatto, 22 June 1889 · New York, N.Y · UCCL03903
- SLC to Elsie Leslie, September 1889 · Unknown place · UCCL09504
- SLC to Henry M. Stanley, 22 November 1889 · Hartford, Conn · UCCL03874
- SLC to William Bowen, 3 December 1889 · Hartford, Conn · UCCL03984
- SLC to Oliver R. Barrett, 19 February 1890 · Hartford, Conn · UCCL04020
- SLC to ? White, 10 June 1893 · Florence, Italy · UCCL04413
- SLC to Unidentified, 25 June 1895 · Elmira, N.Y · UCCL04900
- SLC to H. Walter Barnett, 3 October 1895 · Melbourne, Australia · UCCL04966
- SLC to Orion Clemens and Mollie Clemens, 5 November 1897 · Vienna, Austria · UCCL05310
- SLC to Francis E. Bliss, 25 March 1898 · Vienna, Austria · UCCL05370
- SLC to Chatto & Windus, 16 March 1899 · Vienna, Austria · UCCL05564
- SLC to William Manning, 5 July 1899 · London, England · UCCL05648
- SLC to Richard Watson Gilder, October 1899 · London, England · UCCL05682
- SLC to Dora C. Bowen, 6 June 1900 · London, England · UCCL05814
- SLC to William Archer, 2 August 1900 · London, England · UCCL05847
- SLC to Francis E. Bliss, 16 April 1901 · New York, N.Y · UCCL06038
- SLC to Francis E. Bliss, 26 August 1901 · Saranac Lake, N.Y · UCCL06119
- SLC to Francis E. Bliss, 29 August 1901 · Saranac Lake, N.Y · UCCL06126
- SLC to Francis E. Bliss, 8 September 1901 · Saranac Lake, N.Y · UCCL06131
- SLC to Jules Hart, 26 December 1901 · Riverdale, N.Y · UCCL06197
- SLC to Plasmon Co., 25 April 1902 · Riverdale, N.Y · UCCL06329
- SLC to John Y. MacAlister, 12 April 1904 · Florence, Italy · UCCL06824
- SLC to Elsie Leslie, 21 July 1904 · Lee, Mass · UCCL06899
- SLC to Muriel M. Pears, 23 October 1904 · New York, N.Y · UCCL06935
- SLC to Unidentified, Unknown date · Unknown place · UCCL08020
- SLC per Isabel V. Lyon to L. M. Powers, 9 November 1905 · New York, N.Y · UCCL07202
- SLC per Isabel V. Lyon to Joseph H. Twichell, 26 February 1906 · New York, N.Y · UCCL07356
- SLC per Isabel V. Lyon to Charles H. Clark, 26 February 1906 · New York, N.Y · UCCL07357
- SLC per Isabel V. Lyon to Charles Putzel, 8 March 1906 · New York, N.Y · UCCL07370
- SLC to Bram Stoker, 13 May 1908 · New York, N.Y · UCCL07996
- SLC to Helen Garth, 2 October 1909 · Redding, Conn · UCCL08464
- Jean Clemens to Nannie S. Thaxton, 6 December 1909 · Redding, Conn · UCCL08508
- SLC to Laura ?, Unknown date · Unknown place · UCCL09240
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