MLA
Younans, Oliver J. Letter from Oliver J. Younans (Gordonsville, Virginia) to Cornelia E. Tillinghast (Gillisonville, South Carolina) - April 22, 1864. 1864. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 6, Folder 55. https://digital.library.emory.edu/purl/2150gb5n8t-cor.
APA, 6th edition
Younans, O. J. (1864). Letter from Oliver J. Younans (Gordonsville, Virginia) to Cornelia E. Tillinghast (Gillisonville, South Carolina) - April 22, 1864 (Box 6, Folder 55) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/2150gb5n8t-cor.
Chicago
Younans, Oliver J. “Letter from Oliver J. Younans (Gordonsville, Virginia) to Cornelia E. Tillinghast (Gillisonville, South Carolina) - April 22, 1864.” Letters (correspondence). Civil War Collection, 1864. Box 6, Folder 55. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/2150gb5n8t-cor.