MLA
Key, Benj. W. 1873. Oxford College Library (Oxford, Ga.), Box 1, Folder 50. https://digital.library.emory.edu/purl/972p5hqczr-cor.
APA, 6th edition
Key, Benj. W. (Box 1, Folder 50). (1873). [Black-and-white photographs]. Oxford College Library (Oxford, Ga.). https://digital.library.emory.edu/purl/972p5hqczr-cor.
Chicago
“Key, Benj. W.” Black-and-white photographs. Early Emory College Photographs, 1873. Box 1, Folder 50. Oxford College Library (Oxford, Ga.). https://digital.library.emory.edu/purl/972p5hqczr-cor.