Addressees: Houghton (H. O.) & Co
- Samuel L. Clemens to H. O. Houghton and Company, 5 January 1875 · Hartford, Conn · UCCL01173
- Samuel L. Clemens to H. O. Houghton and Company, 6 January 1875 · Hartford, Conn · UCCL01174
- Samuel L. Clemens to H. O. Houghton and Company, 12 February 1875 · Hartford, Conn · UCCL01192
- Samuel L. Clemens to H. O. Houghton and Company, 28 October 1875 · Hartford, Conn · UCCL01278
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