MLA
Walker, P. B. 1879. Oxford College Library (Oxford, Ga.), Box 2, Folder 20. https://digital.library.emory.edu/purl/385n8pk1r4-cor.
APA, 6th edition
Walker, P. B. (Box 2, Folder 20). (1879). [Black-and-white photographs]. Oxford College Library (Oxford, Ga.). https://digital.library.emory.edu/purl/385n8pk1r4-cor.
Chicago
“Walker, P. B.” Black-and-white photographs. Early Emory College Photographs, 1879. Box 2, Folder 20. Oxford College Library (Oxford, Ga.). https://digital.library.emory.edu/purl/385n8pk1r4-cor.