MLA
Couch, Jackson. Letter from Jackson Couch (Vicksburg, Mississippi) to His Wife, Arminda Couch, and Children - January 6, 1863. 1863. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 2, Folder 29. https://digital.library.emory.edu/purl/293gxd2638-cor.
APA, 6th edition
Couch, J. (1863). Letter from Jackson Couch (Vicksburg, Mississippi) to his wife, Arminda Couch, and children - January 6, 1863 (Box 2, Folder 29) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/293gxd2638-cor.
Chicago
Couch, Jackson. “Letter from Jackson Couch (Vicksburg, Mississippi) to His Wife, Arminda Couch, and Children - January 6, 1863.” Letters (correspondence). Civil War Collection, 1863. Box 2, Folder 29. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/293gxd2638-cor.