MLA
Unidentified Union Officer. Charles D. Fredricks & Co., 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 17, Folder 26. https://digital.library.emory.edu/purl/4472v6wxt1-cor.
APA, 6th edition
Unidentified Union officer (Box 17, Folder 26). (1861). [Cartes-de-visite (card photographs)]. Charles D. Fredricks & Co.; Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/4472v6wxt1-cor.
Chicago
“Unidentified Union Officer.” Cartes-de-visite (card photographs). Civil War Collection. New York, NY: Charles D. Fredricks & Co., 1861. Box 17, Folder 26. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/4472v6wxt1-cor.