MLA
Boyd, W. S. Letter from W. S. Boyd (Williamsburg) to Confederate General Wilmot Gibbes De Saussure Saying That He Is Taking Care of the Estate but Asks for Instructions in Certain Matters - June 28, 1862. 1862. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 3, Folder 3. https://digital.library.emory.edu/purl/484mkkwj69-cor.
APA, 6th edition
Boyd, W. S. (1862). Letter from W. S. Boyd (Williamsburg) to Confederate General Wilmot Gibbes De Saussure saying that he is taking care of the estate but asks for instructions in certain matters - June 28, 1862 (Box 3, Folder 3) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/484mkkwj69-cor.
Chicago
Boyd, W. S. “Letter from W. S. Boyd (Williamsburg) to Confederate General Wilmot Gibbes De Saussure Saying That He Is Taking Care of the Estate but Asks for Instructions in Certain Matters - June 28, 1862.” Letters (correspondence). Civil War Collection, 1862. Box 3, Folder 3. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/484mkkwj69-cor.