MLA
McCollum, A. C. Letter from A. C. McCollum (near Orange County Court House, Virginia) to "Miss M. C." - May 5, 1865. 1865. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 5, Folder 1. https://digital.library.emory.edu/purl/474cnp5jrd-cor.
APA, 6th edition
McCollum, A. C. (1865). Letter from A. C. McCollum (near Orange County Court House, Virginia) to "Miss M. C." - May 5, 1865 (Box 5, Folder 1) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/474cnp5jrd-cor.
Chicago
McCollum, A. C. “Letter from A. C. McCollum (near Orange County Court House, Virginia) to ‘Miss M. C." - May 5, 1865.” Letters (correspondence). Civil War Collection, 1865. Box 5, Folder 1. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/474cnp5jrd-cor.