MLA
Galleries, Brady's National Photographic Portrait. Confederate Politician and Diplomat John Slidell. E. and H. T. Anthony, 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 17, Folder 18. https://digital.library.emory.edu/purl/088qbzkj4k-cor.
APA, 6th edition
Galleries, B. N. P. P. (1861). Confederate politician and diplomat John Slidell (Box 17, Folder 18) [Cartes-de-visite (card photographs)]. E. and H. T. Anthony; Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/088qbzkj4k-cor.
Chicago
Galleries, Brady's National Photographic Portrait. “Confederate Politician and Diplomat John Slidell.” Cartes-de-visite (card photographs). Civil War Collection. New York City, NY: E. and H. T. Anthony, 1861. Box 17, Folder 18. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/088qbzkj4k-cor.