MLA
Orr, J. L. (James Lawrence), 1822-1873. Letter from James Lawrence Orr (Executive Mansion, Columbia, South Carolina) to [unaddressed], vouching for Robert G. Tillinghast - September 14, 1866. September 14, 1866. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/334fn2z470-cor.
APA, 6th edition
Orr, J. L. (James Lawrence), 1822-1873. (September 14, 1866)[Letter from James Lawrence Orr (Executive Mansion, Columbia, South Carolina) to [unaddressed], vouching for Robert G. Tillinghast - September 14, 1866]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/334fn2z470-cor.
Chicago
Orr, J. L. (James Lawrence), 1822-1873, Letter from James Lawrence Orr (Executive Mansion, Columbia, South Carolina) to [unaddressed], vouching for Robert G. Tillinghast - September 14, 1866, September 14, 1866, Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/334fn2z470-cor.