MLA
Dowtin, Tom. Letter from Tom Dowtin, Resident of Cass County, Georgia Who Served in the 18th Georgia Infantry Regiment, to His Mother - November 12, 1860. 1860. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 3, Folder 10. https://digital.library.emory.edu/purl/436tx95z6m-cor.
APA, 6th edition
Dowtin, T. (1860). Letter from Tom Dowtin, resident of Cass County, Georgia who served in the 18th Georgia Infantry Regiment, to his mother - November 12, 1860 (Box 3, Folder 10) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/436tx95z6m-cor.
Chicago
Dowtin, Tom. “Letter from Tom Dowtin, Resident of Cass County, Georgia Who Served in the 18th Georgia Infantry Regiment, to His Mother - November 12, 1860.” Letters (correspondence). Civil War Collection, 1860. Box 3, Folder 10. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/436tx95z6m-cor.