MLA
Spier, John T. Letter from James T. Speir (Fredericksburg, Virginia) to "Dear Sister." James T. Speir Served in the Company C of the 53rd Georgia Infantry Regiment - February 15, 1863. 1863. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 6, Folder 53. https://digital.library.emory.edu/purl/081wdbrvqm-cor.
APA, 6th edition
Spier, J. T. (1863). Letter from James T. Speir (Fredericksburg, Virginia) to "Dear Sister." James T. Speir served in the Company C of the 53rd Georgia Infantry Regiment - February 15, 1863 (Box 6, Folder 53) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/081wdbrvqm-cor.
Chicago
Spier, John T. “Letter from James T. Speir (Fredericksburg, Virginia) to ‘Dear Sister." James T. Speir Served in the Company C of the 53rd Georgia Infantry Regiment - February 15, 1863.” Letters (correspondence). Civil War Collection, 1863. Box 6, Folder 53. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/081wdbrvqm-cor.