MLA
Spencer, Thomas. Tennis Backstop at the National War College at Fort Lesley J. McNair in Washington DC. Supposedly the Spot Where Mary Surratt, Lewis Powell, David Herold, and George Atzerodt Were Executed on July 7, 1865 Due to Their Involvement in the Assassination of President Abraham Lincoln. 1951. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 15, Folder 4. https://digital.library.emory.edu/purl/938jdfn435-cor.
APA, 6th edition
Spencer, T. (1951). Tennis backstop at the National War College at Fort Lesley J. McNair in Washington DC. Supposedly the spot where Mary Surratt, Lewis Powell, David Herold, and George Atzerodt were executed on July 7, 1865 due to their involvement in the assassination of President Abraham Lincoln (Box 15, Folder 4) [Black-and-white photographs]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/938jdfn435-cor.
Chicago
Spencer, Thomas. “Tennis Backstop at the National War College at Fort Lesley J. McNair in Washington DC. Supposedly the Spot Where Mary Surratt, Lewis Powell, David Herold, and George Atzerodt Were Executed on July 7, 1865 Due to Their Involvement in the Assassination of President Abraham Lincoln.” Black-and-white photographs. Civil War Collection, 1951. Box 15, Folder 4. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/938jdfn435-cor.