MLA
Fauvails, Sam. Letter from Sam Fauvails (Pulack's House) to A. C. Richards - February 19, [No Year]. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 3, Folder 24. https://digital.library.emory.edu/purl/972p5hqd0k-cor.
APA, 6th edition
Fauvails, S. Letter from Sam Fauvails (Pulack's House) to A. C. Richards - February 19, [no year] (Box 3, Folder 24) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/972p5hqd0k-cor.
Chicago
Fauvails, Sam. “Letter from Sam Fauvails (Pulack's House) to A. C. Richards - February 19, [No Year].” Letters (correspondence). Civil War Collection, n.d. Box 3, Folder 24. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/972p5hqd0k-cor.