MLA
Hitt, David M. Letter from David M. Hitt, to His Wife Jane A. Hitt - October, 1862. 1862. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 3, Folder 60. https://digital.library.emory.edu/purl/423612jn88-cor.
APA, 6th edition
Hitt, D. M. (1862). Letter from David M. Hitt, to his wife Jane A. Hitt - October, 1862 (Box 3, Folder 60) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/423612jn88-cor.
Chicago
Hitt, David M. “Letter from David M. Hitt, to His Wife Jane A. Hitt - October, 1862.” Letters (correspondence). Civil War Collection, 1862. Box 3, Folder 60. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/423612jn88-cor.