MLA
Nielson, N. M. Alligator Hunt, near Port Arthur, Tex. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 69. https://digital.library.emory.edu/purl/064tht76n2-cor.
APA, 6th edition
Nielson, N. M. Alligator hunt, near Port Arthur, Tex. (Box 69) [Photographic postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/064tht76n2-cor.
Chicago
Nielson, N. M. “Alligator Hunt, near Port Arthur, Tex.” Photographic 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/064tht76n2-cor.