Sources: CPlh2
- Samuel L. Clemens to Unidentified, 1 September 1879 · SS Gallia, en route from Liverpool, England, to New York, N.Y · UCCL12027
- Clara L. Clemens to Grace E. King, 28 December 1887 · Hartford, Conn · UCCL03686
- Susy (Olivia Susan) Clemens to Grace E. King, 1 January 1888 · Hartford, Conn · UCCL03689
- Clara L. Clemens to Grace E. King, 29 April 1888 · Hartford, Conn · UCCL03720
- OLC to Grace E. King, 17 June–7 August 1888 · Hartford, Conn · UCCL03724
- Clara L. Clemens to Grace E. King, 29 July 1888 · Elmira, N.Y · UCCL03744
- Susy Clemens to Grace E. King, 23 or 24 August 1888 · Elmira, N.Y · UCCL03754
- Clara L. Clemens to Grace E. King, 23 or 24 August 1888 · Elmira, N.Y · UCCL03746
- SLC to Grace E. King, 12 and 13 September 1888 · Elmira, N.Y · UCCL03760
- SLC to Grace E. King, 24 October 1888 · New York, N.Y · UCCL03794
- SLC to Grace E. King, 16 November 1888 · Hartford, Conn · UCCL03833
- OLC and SLC to Grace E. King, 4 December 1888 · Hartford, Conn · UCCL03799
- Susy (Olivia Susan) Clemens to Grace E. King, 6 December 1888 · Hartford, Conn · UCCL04145
- Clara L. Clemens to Grace E. King, 22 December 1888 · Hartford, Conn · UCCL04144
- Clara L. Clemens to Grace E. King, 3 February 1889 · Hartford, Conn · UCCL03857
- Jean Clemens to Grace E. King, 10 February 1889 · Unknown place · UCCL03862
- Susy Clemens to Grace E. King, 23–28 February 1889, Hartford, Conn · UCCL04146
- Clara L. Clemens to Grace E. King, 7 and 8 March 1889 · Hartford, Conn · UCCL03870
- OLC to Grace E. King, 24 and 25 March 1889 · Hartford, Conn · UCCL03877
- Clara L. Clemens to Grace E. King, 4–12 April 1889, Hartford, Conn · UCCL03818
- Susy Clemens to Grace E. King, 21–23 April 1889 · Hartford, Conn · UCCL03878
- OLC to Grace E. King, 25 February 1890 · Hartford, Conn · UCCL04021
- OLC to Grace E. King, 10 September 1890 · Tannersville, N.Y · UCCL04093
- OLC to Grace E. King, 14 January 1891 · Hartford, Conn · UCCL04159
- OLC to Grace E. King, 28 May 1891 · Hartford, Conn · UCCL04212
- OLC to Grace E. King, 23 August 1891 · Marienbad, Germany · UCCL04224
- OLC to Grace E. King, 20 May 1892 · Venice, Italy · UCCL04209
- OLC to Grace E. King, 1 July 1892 · Bad Nauheim, Germany · UCCL01558
- OLC to Grace E. King, 30 August and 2 September 1892 · Bad Nauheim, Germany · UCCL01880
- OLC to Grace E. King, 5 September 1892 · Bad Nauheim, Germany · UCCL02071
- Jean Clemens to Grace E. King, 19 November 1892, Florence, Italy · UCCL08956
- OLC to Grace E. King, 13 or 14 June 1893 · Florence, Italy · UCCL04417
- OLC to Grace E. King, 5 November 1893 · Paris, France · UCCL04489
- OLC to Grace E. King, 16 May and 3 June 1894 · Paris, France · UCCL04733
- OLC to Grace E. King, 16? June 1894 · Paris, France · UCCL08665
- OLC to Grace E. King, 9 March 1897 · London, England · UCCL05185
- OLC to Grace E. King, 27 June 1897 · London, England · UCCL05235
- OLC to Grace E. King, December 1899 · London, England · UCCL05729
- OLC to Grace E. King, January–June 1900, London, England · UCCL05728
- OLC to Grace E. King, 15 and 24 February 1901 · New York, N.Y · UCCL05999
- Clara L. Clemens to Grace E. King, 22 June 1903 · Riverdale, N.Y · UCCL06375
- SLC to Grace E. King, 21 June 1904 · Florence, Italy · UCCL06846
- SLC to Grace E. King, after 26 December 1909 · Redding, Conn · UCCL06962
- OLC to Grace E. King, Unknown date · Unknown place · UCCL08955
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