MLA
Adolph Selige Pub. Co. (St. Louis, Mo.). Happy little darkeys : two smiling African American boys [hand colored]. unknown. Robert Langmuir African American Photograph Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/679573n5wk-cor.
APA, 6th edition
Adolph Selige Pub. Co. (St. Louis, Mo.). (unknown)[Happy little darkeys : two smiling African American boys [hand colored]]. Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/679573n5wk-cor.
Chicago
Adolph Selige Pub. Co. (St. Louis, Mo.), Happy little darkeys : two smiling African American boys [hand colored], unknown, Robert Langmuir African American Photograph Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/679573n5wk-cor.