MLA
Co., Detroit Publishing. Whoa Mule! : Four African American Children Sitting on a Mule in Front of a Log Cabin and a Woman Looking out the Window [Hand Colored]. 1916. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 72. https://digital.library.emory.edu/purl/757np5hqdx-cor.
APA, 6th edition
Co., D. P. (1916). Whoa mule! : four African American children sitting on a mule in front of a log cabin and a woman looking out the window [hand colored] (Box 72) [Postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/757np5hqdx-cor.
Chicago
Co., Detroit Publishing. “Whoa Mule! : Four African American Children Sitting on a Mule in Front of a Log Cabin and a Woman Looking out the Window [Hand Colored].” Postcards. Robert Langmuir African American Photograph Collection, 1916. Box 72. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/757np5hqdx-cor.