MLA
Harper. Ethel Gertrude Harper at 1 Years Old, Standing on a Chair, in Johnston, Tex. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 61. https://digital.library.emory.edu/purl/453wstqjs8-cor.
APA, 6th edition
H. Ethel Gertrude Harper at 1 years old, standing on a chair, in Johnston, Tex. (Box 61) [Card photographs (photographs)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/453wstqjs8-cor.
Chicago
Harper. “Ethel Gertrude Harper at 1 Years Old, Standing on a Chair, in Johnston, Tex.” Card photographs (photographs). Robert Langmuir African American Photograph Collection, n.d. Box 61. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/453wstqjs8-cor.