MLA
C., L. E. Letter from Civilian [Initials L.E.C.] to "My Dear Aunt Amanda," Discussing Family News. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 6, Folder 61. https://digital.library.emory.edu/purl/102c866tr1-cor.
APA, 6th edition
C., L. E. Letter from civilian [initials L.E.C.] to "My dear Aunt Amanda," discussing family news (Box 6, Folder 61) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/102c866tr1-cor.
Chicago
C., L. E. “Letter from Civilian [Initials L.E.C.] to ‘My Dear Aunt Amanda," Discussing Family News.” Letters (correspondence). Civil War Collection, n.d. Box 6, Folder 61. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/102c866tr1-cor.