Addressees: Laffan, William Mackay
- Samuel L. Clemens to William Mackay Laffan, 20? February 1880 · Hartford, Conn · UCCL06202 CU-MARK
- SLC, OLC to Laurence Hutton, Eleanor V. Hutton, and William M. Laffan and Georgiana R. Laffan, 25 February 1886 · Hartford, Conn · UCCL03372 MH-H, NjP
- SLC to Frederick J. Hall and William M. Laffan, 6 August 1886 · Elmira, N.Y · UCCL02640 NN-BGC, ViU
- SLC to William Mackay Laffan, 28 September 1888 · Hartford, Conn · UCCL03776 CU-MARK
- SLC to William M. and Georgiana R. Laffan, 20 October 1898 · Vienna, Austria · UCCL13010 CU-MARK
- SLC to William Mackay Laffan, 28 November 1902 · New York, N.Y · UCCL09407 NN-BGC
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