MLA
Krebbs, S. H., and Co. Washington School (Colored.) in Enid, Okla. [Hand Colored]. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 69. https://digital.library.emory.edu/purl/474cnp5htk-cor.
APA, 6th edition
Krebbs, S. H., & C. Washington School (Colored.) in Enid, Okla. [hand colored] (Box 69) [Postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/474cnp5htk-cor.
Chicago
Krebbs, S. H., and Co. “Washington School (Colored.) in Enid, Okla. [Hand Colored].” Postcards. Robert Langmuir African American Photograph Collection, n.d. Box 69. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/474cnp5htk-cor.