MLA
Richards, Henry. Letter from Henry Richards (Fort Johnson, James Island, South Carolina) to His Mother (Savannah, Georgia) - September 7, 1863. 1863. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 5, Folder 62. https://digital.library.emory.edu/purl/136h18943j-cor.
APA, 6th edition
Richards, H. (1863). Letter from Henry Richards (Fort Johnson, James Island, South Carolina) to his mother (Savannah, Georgia) - September 7, 1863 (Box 5, Folder 62) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/136h18943j-cor.
Chicago
Richards, Henry. “Letter from Henry Richards (Fort Johnson, James Island, South Carolina) to His Mother (Savannah, Georgia) - September 7, 1863.” Letters (correspondence). Civil War Collection, 1863. Box 5, Folder 62. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/136h18943j-cor.