MLA
Harper. Little Amos Harper, Age 5 Years and 1 Month, Taken Jan. 8, 1900. 1900. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 61. https://digital.library.emory.edu/purl/883xsj3v17-cor.
APA, 6th edition
H. (1900). Little Amos Harper, age 5 years and 1 month, taken Jan. 8, 1900 (Box 61) [Card photographs (photographs)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/883xsj3v17-cor.
Chicago
Harper. “Little Amos Harper, Age 5 Years and 1 Month, Taken Jan. 8, 1900.” Card photographs (photographs). Robert Langmuir African American Photograph Collection, 1900. Box 61. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/883xsj3v17-cor.