MLA
Krebbs, S. H., and Co. The Magnolia High School, (Colored) Valdosta, Ga. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 69. https://digital.library.emory.edu/purl/279v15dv7n-cor.
APA, 6th edition
Krebbs, S. H., & C. The Magnolia High School, (colored) Valdosta, Ga. (Box 69) [Postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/279v15dv7n-cor.
Chicago
Krebbs, S. H., and Co. “The Magnolia High School, (Colored) Valdosta, Ga.” 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/279v15dv7n-cor.