Sources: RPB-JH
- SLC to Unidentified, November to 15 December? 1879 · Unknown place · UCCL13217 RPB-JH
- John M. Hay to SLC, 14 April 1885 · Cleveland, Ohio · UCLC42477 RPB-JH
- SLC to John M. Hay, 28 June 1901 · Saranac Lake, N.Y · UCCL06080 RPB-JH
- SLC to Joseph H. Twichell, 18 January 1902 · Riverdale, N.Y · UCCL06249 RPB-JH
- SLC to James J. Roche, 11 April 1905 · New York, N.Y · UCCL07031 CU-MARK, RPB-JH
- SLC to Harper’s Weekly editor, 3 October 1905 · Dublin, N.H · UCCL07160 RPB-JH
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