MLA
Beard, Louisa H. Letter from Louisa H. Beard (Waltham, Massachusetts) to "My Dear Sister," [Somewhere in the South] Regarding the Aftermath of the War on the Family and Life in Waltham - January 7, 1866. 1866. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 8, Folder 6. https://digital.library.emory.edu/purl/723hx3fg1c-cor.
APA, 6th edition
Beard, L. H. (1866). Letter from Louisa H. Beard (Waltham, Massachusetts) to "My dear sister," [somewhere in the South] regarding the aftermath of the war on the family and life in Waltham - January 7, 1866 (Box 8, Folder 6) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/723hx3fg1c-cor.
Chicago
Beard, Louisa H. “Letter from Louisa H. Beard (Waltham, Massachusetts) to ‘My Dear Sister," [Somewhere in the South] Regarding the Aftermath of the War on the Family and Life in Waltham - January 7, 1866.” Letters (correspondence). Civil War Collection, 1866. Box 8, Folder 6. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/723hx3fg1c-cor.