MLA
Grimes, N. M. Letter from N. M. Grimes to Sarah Ann Scott about the Death of Her Husband, Alexander - February 22, 1865. 1865. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 6, Folder 15. https://digital.library.emory.edu/purl/849t1g1kjz-cor.
APA, 6th edition
Grimes, N. M. (1865). Letter from N. M. Grimes to Sarah Ann Scott about the death of her husband, Alexander - February 22, 1865 (Box 6, Folder 15) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/849t1g1kjz-cor.
Chicago
Grimes, N. M. “Letter from N. M. Grimes to Sarah Ann Scott about the Death of Her Husband, Alexander - February 22, 1865.” Letters (correspondence). Civil War Collection, 1865. Box 6, Folder 15. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/849t1g1kjz-cor.