MLA
Morris, W. S. (William S.). [Letter of William S. Morris, president of the southern telegraph companies, to J.H. Reagan, postmaster-general of the Confederate States of America].. 1862. Civil War Imprints. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/252j6q5bfc-cor.
APA, 6th edition
Morris, W. S. (William S.). (1862)[[Letter of William S. Morris, president of the southern telegraph companies, to J.H. Reagan, postmaster-general of the Confederate States of America].]. Civil War Imprints, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/252j6q5bfc-cor.
Chicago
Morris, W. S. (William S.), [Letter of William S. Morris, president of the southern telegraph companies, to J.H. Reagan, postmaster-general of the Confederate States of America]., 1862, Civil War Imprints, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/252j6q5bfc-cor.