References

1. Harvard University, Houghton Library, Cambridge, Mass.
2. Machlis, Paul, ed. Union Catalog of Clemens Letters. Edited by Paul Machlis. Berkeley, Los Angeles, London: University of California Press. [In some cases, UCCL catalog numbers cited in this volume supersede those assigned in 1986 and reflect corrections or additions to the catalog since publication. An updated version of the catalog can be consulted via the Letters Search page at MTPO.] 1986
3. Microfilm Edition of Mark Twain’s Previously Unpublished Letters. Prepared by Anh Quynh Bui, Victor Fischer, Michael B. Frank, Robert H. Hirst, Lin Salamo, and Harriet Elinor Smith. 8 vols. Berkeley: The Bancroft Library. 2001