Sources: MoHi
- SLC to Daniel Slote, 31 March 1881 · Hartford, Conn · UCCL01933
- SLC to Florence Hayward, 29 October 1896 · London, England · UCCL05139
- SLC to Florence Hayward, 29 January 1897 · London, England · UCCL05174
- SLC to Florence Hayward, 3 July 1897 · London, England · UCCL05255
- OLC to Florence Hayward, 6 July 1897 · London, England · UCCL05247
- SLC to Bertha von Suttner, 17 February 1898 · Vienna, Austria · UCCL05351
- SLC to Bertha von Suttner, 27 March 1899 · Budapest, Hungary · UCCL05569
- SLC to Florence Hayward, 6 July 1901 · Saranac Lake, N.Y · UCCL06085
- SLC to George Iles, 26 May 1902 · Riverdale, N.Y · UCCL06346
- SLC per Isabel V. Lyon to George F. Mockler, 1‒31 December 1902 · Riverdale, N.Y · UCCL06535
- SLC to Unidentified, 4 January 1909 · New York, N.Y · UCCL08309
1