MLA
Brown, George W. (George Washington), 1820-1915. Portrait of a man in suit, trenchcoat and hat standing next to a woman in a dress, hat and coat seated in a chair. unknown. Robert Langmuir African American Photograph Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/996k0p2np5-cor.
APA, 6th edition
Brown, George W. (George Washington), 1820-1915. (unknown)[Portrait of a man in suit, trenchcoat and hat standing next to a woman in a dress, hat and coat seated in a chair]. Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/996k0p2np5-cor.
Chicago
Brown, George W. (George Washington), 1820-1915, Portrait of a man in suit, trenchcoat and hat standing next to a woman in a dress, hat and coat seated in a chair, unknown, Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/996k0p2np5-cor.