MLA
McKinney, Chris C. Envelope Containing Letter from Christ C. McKinney (Camp in Alabama) to His Wife, Mary (Petersburg, Tennessee). McKinney Served in the 8th Tennessee Infantry Regiment - November 8, 1864. 1864. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 5, Folder 7. https://digital.library.emory.edu/purl/996k0p2pjn-cor.
APA, 6th edition
McKinney, C. C. (1864). Envelope containing letter from Christ C. McKinney (Camp in Alabama) to his wife, Mary (Petersburg, Tennessee). McKinney served in the 8th Tennessee Infantry Regiment - November 8, 1864 (Box 5, Folder 7) [Envelopes]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/996k0p2pjn-cor.
Chicago
McKinney, Chris C. “Envelope Containing Letter from Christ C. McKinney (Camp in Alabama) to His Wife, Mary (Petersburg, Tennessee). McKinney Served in the 8th Tennessee Infantry Regiment - November 8, 1864.” Envelopes. Civil War Collection, 1864. Box 5, Folder 7. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/996k0p2pjn-cor.