Sources: CLSU
- Samuel L. Clemens to George L. Hutchings, 15 October 1868 · Hartford, Conn · UCCL11875
- Samuel L. Clemens to George L. Hutchings, 21 September 1869 · Buffalo, N. Y · UCCL11876
- Samuel L. Clemens to George L. Hutchings, 1 January 1870 · Elmira, N.Y · UCCL11877
- Samuel L. Clemens to George L. Hutchings, 13 August 1870 · Elmira, N. Y · UCCL11913
- Samuel L. Clemens to Adolph H. Sutro, 24 July 1871 · Elmira, N.Y · UCCL00640
- SLC to Hamlin Garland, 28 July 1883 · Elmira, N.Y · UCCL02063
- SLC per Unidentified Amanuensis to Hamlin Garland, 23 March 1889 · Hartford, Conn · UCCL03875
- SLC to Thomas Wardle, 4 May 1904 · Florence, Italy · UCCL06829
- SLC to Hamlin Garland, 20 May 1905 · Dublin, N.H · UCCL07047
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