MLA
Cuyler, Richard M. Letter from Richard M. Cuyler (142 Pearl Street, New York) to John Williamson (Savannah, Georgia) - September 1, 1867. 1867. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 2, Folder 42. https://digital.library.emory.edu/purl/668x95x7bh-cor.
APA, 6th edition
Cuyler, R. M. (1867). Letter from Richard M. Cuyler (142 Pearl Street, New York) to John Williamson (Savannah, Georgia) - September 1, 1867 (Box 2, Folder 42) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/668x95x7bh-cor.
Chicago
Cuyler, Richard M. “Letter from Richard M. Cuyler (142 Pearl Street, New York) to John Williamson (Savannah, Georgia) - September 1, 1867.” Letters (correspondence). Civil War Collection, 1867. Box 2, Folder 42. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/668x95x7bh-cor.