MLA
Chambers, [Hat?]. Letter from [Hat?] Chambers to her "mother" - July 31, 1863. July 31, 1863. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/904dncjv09-cor.
APA, 6th edition
Chambers, [Hat?]. (July 31, 1863)[Letter from [Hat?] Chambers to her "mother" - July 31, 1863]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/904dncjv09-cor.
Chicago
Chambers, [Hat?], Letter from [Hat?] Chambers to her "mother" - July 31, 1863, July 31, 1863, Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/904dncjv09-cor.