MLA
Willcox, Caroline M. Letter from Caroline M. Willcox (Jacksonville, Florida) to "Dear Lind" - November 26, 1861. 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 7, Folder 28. https://digital.library.emory.edu/purl/409j3txb7f-cor.
APA, 6th edition
Willcox, C. M. (1861). Letter from Caroline M. Willcox (Jacksonville, Florida) to "Dear Lind" - November 26, 1861 (Box 7, Folder 28) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/409j3txb7f-cor.
Chicago
Willcox, Caroline M. “Letter from Caroline M. Willcox (Jacksonville, Florida) to ‘Dear Lind’ - November 26, 1861.” Letters (correspondence). Civil War Collection, 1861. Box 7, Folder 28. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/409j3txb7f-cor.