MLA
Memminger, C. G. (Christopher Gustavus), 1803-1888. Letter from C. G. Memminger (Montgomery, Alabama) to David Flavel Jamison (Charleston, South Carolina) about the mustering of South Carolina troops - March 2, 1861. March 2, 1861. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/873pvmcwgf-cor.
APA, 6th edition
Memminger, C. G. (Christopher Gustavus), 1803-1888. (March 2, 1861)[Letter from C. G. Memminger (Montgomery, Alabama) to David Flavel Jamison (Charleston, South Carolina) about the mustering of South Carolina troops - March 2, 1861]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/873pvmcwgf-cor.
Chicago
Memminger, C. G. (Christopher Gustavus), 1803-1888, Letter from C. G. Memminger (Montgomery, Alabama) to David Flavel Jamison (Charleston, South Carolina) about the mustering of South Carolina troops - March 2, 1861, March 2, 1861, Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/873pvmcwgf-cor.