MLA
Rogers, John. Letter from John Rogers to W. C. Roger. Rogers Served in Company E of the 12th Alabama Infantry Regiment. 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 6, Folder 3. https://digital.library.emory.edu/purl/218dfn2ztv-cor.
APA, 6th edition
Rogers, J. (1861). Letter from John Rogers to W. C. Roger. Rogers served in Company E of the 12th Alabama Infantry Regiment (Box 6, Folder 3) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/218dfn2ztv-cor.
Chicago
Rogers, John. “Letter from John Rogers to W. C. Roger. Rogers Served in Company E of the 12th Alabama Infantry Regiment.” Letters (correspondence). Civil War Collection, 1861. Box 6, Folder 3. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/218dfn2ztv-cor.