MLA
Baade, Lyle E. Letter from Lyle E. Baade (Witchita, Kansas) to Drew Gilpin Faust (Philadelphia, Pennsylvania) Regarding Information about the Johnson Family of Coweta and Campbell County, Georgia Including Information about the Group Portrait. 1996. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 17, Folder 39. https://digital.library.emory.edu/purl/81289320js-cor.
APA, 6th edition
Baade, L. E. (1996). Letter from Lyle E. Baade (Witchita, Kansas) to Drew Gilpin Faust (Philadelphia, Pennsylvania) regarding information about the Johnson family of Coweta and Campbell County, Georgia including information about the group portrait (Box 17, Folder 39) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/81289320js-cor.
Chicago
Baade, Lyle E. “Letter from Lyle E. Baade (Witchita, Kansas) to Drew Gilpin Faust (Philadelphia, Pennsylvania) Regarding Information about the Johnson Family of Coweta and Campbell County, Georgia Including Information about the Group Portrait.” Letters (correspondence). Civil War Collection, 1996. Box 17, Folder 39. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/81289320js-cor.